CLOUDFLARE, INC., 10-K filed on 2/25/2021
Annual Report
v3.20.4
Cover Page - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Feb. 12, 2021
Jun. 30, 2020
Document Information [Line Items]      
Document Type 10-K    
Document Annual Report true    
Document Period End Date Dec. 31, 2020    
Current Fiscal Year End Date --12-31    
Document Transition Report false    
Entity File Number 001-39039    
Entity Registrant Name Cloudflare, Inc.    
Entity Incorporation, State or Country Code DE    
Entity Tax Identification Number 27-0805829    
Entity Address, Address Line One 101 Townsend Street    
Entity Address, City or Town San Francisco    
Entity Address, State or Province CA    
Entity Address, Postal Zip Code 94107    
City Area Code 888    
Local Phone Number 993-5273    
Title of 12(b) Security Class A Common Stock, $0.001 par value    
Trading Symbol NET    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Filer Category Large Accelerated Filer    
Entity Small Business false    
Entity Emerging Growth Company false    
ICFR Auditor Attestation Flag true    
Entity Shell Company false    
Entity Public Float     $ 4,336
Amendment Flag false    
Entity Central Index Key 0001477333    
Document Fiscal Period Focus FY    
Document Fiscal Year Focus 2020    
Documents Incorporated by Reference Portions of the registrant's definitive Proxy Statement relating to the 2021 Annual Meeting of Stockholders are incorporated herein by reference in Part III of this Annual Report on Form 10-K to the extent stated herein. Such Proxy Statement will be filed with the Securities and Exchange Commission within 120 days of the registrant's fiscal year ended December 31, 2020.    
Class A common stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   250,305,083  
Class B common stock      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding   58,520,694  
v3.20.4
CONSOLIDATED BALANCE SHEETS - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Current assets:    
Cash and cash equivalents $ 108,895 $ 138,976
Available-for-sale securities 923,201 497,972
Accounts receivable, net 63,499 33,867
Contract assets 3,538 2,063
Restricted cash short-term 2,591 0
Prepaid expenses and other current assets 28,230 16,994
Total current assets 1,129,954 689,872
Property and equipment, net 123,688 101,466
Goodwill 17,167 4,083
Acquired intangible assets, net 2,800 31
Operating lease right-of-use assets 43,148 0
Deferred contract acquisition costs, noncurrent 44,176 25,184
Restricted cash 6,660 6,660
Other noncurrent assets 13,058 3,528
Total assets 1,380,651 830,824
Current liabilities:    
Accounts payable 14,485 11,463
Accrued expenses and other current liabilities 45,627 28,314
Operating lease liabilities 17,717 0
Liability for early exercise of unvested stock options 8,603 13,263
Deferred revenue 54,945 30,843
Total current liabilities 141,377 83,883
Convertible senior notes, net 383,275 0
Build-to-suit lease financing obligation   10,506
Operating lease liabilities, noncurrent 27,309 0
Deferred revenue, noncurrent 1,891 804
Other noncurrent liabilities 9,859 9,803
Total liabilities 563,711 104,996
Commitments and contingencies (Note 8)
Stockholders’ Equity    
Additional paid-in capital 1,236,993 1,027,179
Accumulated deficit (420,520) (301,706)
Accumulated other comprehensive income 163 61
Total stockholders’ equity 816,940 725,828
Total liabilities and stockholders’ equity 1,380,651 830,824
Class A common stock    
Stockholders’ Equity    
Common stock 249 87
Class B common stock    
Stockholders’ Equity    
Common stock $ 55 $ 207
v3.20.4
CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares
Dec. 31, 2020
Dec. 31, 2019
Class A common stock    
Stockholders’ Equity    
Common stock, par value (in dollars per share) $ 0.001 $ 0.001
Common stock, shares authorized (in shares) 2,250,000,000 2,250,000,000
Common stock, shares issued (in shares) 249,401,232 87,071,783
Common stock, shares outstanding (in shares) 249,401,232 87,071,783
Class B common stock    
Stockholders’ Equity    
Common stock, par value (in dollars per share) $ 0.001 $ 0.001
Common stock, shares authorized (in shares) 315,000,000 315,000,000
Common stock, shares issued (in shares) 59,238,742 213,101,364
Common stock, shares outstanding (in shares) 59,238,742 213,101,364
v3.20.4
CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($)
shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Statement [Abstract]      
Revenue $ 431,059 $ 287,022 $ 192,674
Cost of revenue 101,055 63,423 43,537
Gross profit 330,004 223,599 149,137
Operating expenses:      
Sales and marketing 217,875 159,298 94,394
Research and development 127,144 90,669 54,463
General and administrative 91,753 81,578 85,179
Total operating expenses 436,772 331,545 234,036
Loss from operations (106,768) (107,946) (84,899)
Non-operating income (expense):      
Interest income 6,588 5,787 1,895
Interest expense (24,964) (1,112) (992)
Other income (expense), net 171 (1,442) (2,091)
Total non-operating income (expense), net (18,205) 3,233 (1,188)
Loss before income taxes (124,973) (104,713) (86,087)
Provision for (benefit from) income taxes (5,603) 1,115 1,077
Net loss $ (119,370) $ (105,828) $ (87,164)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share) $ (0.40) $ (0.72) $ (1.08)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares) 299,774 146,306 80,981
v3.20.4
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Statement of Comprehensive Income [Abstract]      
Net loss $ (119,370) $ (105,828) $ (87,164)
Other comprehensive income:      
Change in unrealized gain on investments, net of tax 102 118 49
Other comprehensive income 102 118 49
Comprehensive loss $ (119,268) $ (105,710) $ (87,115)
v3.20.4
CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS’ EQUITY (DEFICIT) - USD ($)
$ in Thousands
Total
Cumulative Effect, Period of Adoption, Adjustment
Common Stock
Additional paid-in capital
Accumulated deficit
Accumulated deficit
Cumulative Effect, Period of Adoption, Adjustment
Accumulated other comprehensive income (loss)
Redeemable convertible preferred stock
Class A common stock
Class A common stock
Common Stock
Class B common stock
Class B common stock
Common Stock
Beginning balance (in shares) at Dec. 31, 2017               152,022,000        
Beginning balance at Dec. 31, 2017               $ 181,546        
Increase (Decrease) in Temporary Equity [Roll Forward]                        
Issuance of Series D redeemable convertible preferred stock, net of issuance costs of $25 (in shares)               13,636,000        
Issuance of Series D redeemable convertible preferred stock, net of issuance costs of $25               $ 149,975        
Ending balance (in shares) at Dec. 31, 2018               165,658,000        
Ending balance at Dec. 31, 2018               $ 331,521        
Beginning balance (in shares) at Dec. 31, 2017                   0   79,116,000
Beginning balance at Dec. 31, 2017 $ (59,834)     $ 48,907 $ (108,714)   $ (106)     $ 0   $ 79
Increase (Decrease) in Stockholders' Equity [Roll Forward]                        
Issuance of common stock upon exercise of stock options (in shares) 12,387,000                     5,481,000
Issuance of common stock upon exercise of stock options $ 4,412     4,406               $ 6
Repurchases of unvested common stock (in shares)                       (36,000)
Issuance of common stock related to early exercised stock options (in shares)                       6,906,000
Vesting of shares issued upon early exercise of stock options 1,415     1,415                
Vesting of restricted stock (in shares)                       75,000
Vesting of restricted common stock 3     3                
Stock-based compensation 27,614     27,614                
Net loss (87,164)   $ (87,164)   (87,164)              
Other comprehensive income 49           49          
Ending balance (in shares) at Dec. 31, 2018                   0   91,542,000
Ending balance at Dec. 31, 2018 $ (113,505)     82,345 (195,878)   (57)     $ 0   $ 85
Accounting Standards Update [Extensible List] us-gaap:AccountingStandardsUpdate201602Member                      
Increase (Decrease) in Temporary Equity [Roll Forward]                        
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)               (165,658,000)        
Conversion of redeemable convertible preferred stock to common stock upon initial public offering               $ (331,521)        
Ending balance (in shares) at Dec. 31, 2019               0        
Ending balance at Dec. 31, 2019               $ 0        
Increase (Decrease) in Stockholders' Equity [Roll Forward]                        
Issuance of common stock upon initial public offering, net of underwriting discounts and issuance costs (in shares)                   40,250,000    
Issuance of common stock upon initial public offering, net of underwriting discounts and issuance costs $ 565,041     565,001           $ 40    
Conversion of redeemable convertible preferred stock to common stock upon initial public offering (in shares)                   31,381,000   134,277,000
Conversion of redeemable convertible preferred stock to common stock upon initial public offering 331,521     331,355           $ 31   $ 135
Conversion of redeemable convertible preferred stock warrants into common stock warrants and issuance of common stock upon net exercise of common stock warrants (in shares)                       174,000
Conversion of redeemable convertible preferred stock warrants into common stock warrants and issuance of common stock upon net exercise of common stock warrants 3,135     3,135                
Issuance of common stock in connection with acquisition (in shares)                       7,000
Issuance of common stock in connection with acquisition $ 18     18                
Issuance of common stock upon exercise of stock options (in shares) 2,665,000                 27,000   1,736,000
Issuance of common stock upon exercise of stock options $ 3,058     3,055           $ 1   $ 2
Repurchases of unvested common stock (in shares)                       (123,000)
Issuance of common stock related to early exercised stock options (in shares)                       902,000
Vesting of shares issued upon early exercise of stock options 3,668     3,668                
Conversion of Class B to Class A common stock (in shares)                   15,414,000   15,414,000
Conversion of Class B to Class A common stock                   $ 15   $ (15)
Stock-based compensation 38,602     38,602                
Net loss (105,828)       (105,828)         $ (18,259)   $ (87,569)
Other comprehensive income 118           118          
Ending balance (in shares) at Dec. 31, 2019                 87,071,783 87,072,000 213,101,364 213,101,000
Ending balance at Dec. 31, 2019 725,828 $ 556   1,027,179 (301,706) $ 556 61     $ 87   $ 207
Ending balance (in shares) at Dec. 31, 2020               0        
Ending balance at Dec. 31, 2020               $ 0        
Increase (Decrease) in Stockholders' Equity [Roll Forward]                        
Issuance of common stock in connection with acquisition (in shares)                   107,000    
Issuance of common stock in connection with acquisition $ 1,821     1,821                
Issuance of unvested restricted stock in connection with acquisition (in shares)                   841,000    
Issuance of common stock upon exercise of stock options (in shares) 4,451,000                     4,351,000
Issuance of common stock upon exercise of stock options $ 7,457     7,453               $ 4
Repurchases of unvested common stock (in shares)                   (64,000)    
Issuance of common stock related to early exercised stock options (in shares)                       100,000
Vesting of shares issued upon early exercise of stock options 4,744     4,742               $ 2
Vesting of restricted stock (in shares)                   487,000   2,446,000
Vesting of restricted common stock 0     (3)               $ 3
Tax withholding on RSU settlement (in shares)                   (10,000)   (418,000)
Tax withholding on RSU settlement (8,101)     (8,101)                
Conversion of Class B to Class A common stock (in shares)                   160,341,000   160,341,000
Conversion of Class B to Class A common stock 0                 $ 161   $ (161)
Equity component of convertible senior notes, net of issuance costs 200,812     200,812                
Purchases of capped calls related to convertible senior notes (67,333)     (67,333)                
Common stock issued under employee stock purchase plan (in shares)                   640,000    
Common stock issued under employee stock purchase plan 10,924     10,923           $ 1    
Tax withholding on common stock issued under employee stock purchase plan (in shares)                   (13,000)    
Tax withholding on common stock issued under employee stock purchase plan (376)     (376)                
Stock-based compensation 59,876     59,876                
Net loss (119,370)       (119,370)         $ (70,955)   $ (48,415)
Other comprehensive income 102           102          
Ending balance (in shares) at Dec. 31, 2020                 249,401,232 249,401,000 59,238,742 59,239,000
Ending balance at Dec. 31, 2020 $ 816,940     $ 1,236,993 $ (420,520)   $ 163     $ 249   $ 55
v3.20.4
CONSOLIDATED STATEMENTS OF REDEEMABLE CONVERTIBLE PREFERRED STOCK AND STOCKHOLDERS' EQUITY (DEFICIT) (Parenthetical)
$ in Thousands
 12 Months Ended
Dec. 31, 2018
USD ($)
Issuance cost, equity component $ 0
Redeemable convertible preferred stock  
Issuance cost, equity component $ 25
v3.20.4
CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Cash Flows From Operating Activities      
Net loss $ (119,370) $ (105,828) $ (87,164)
Adjustments to reconcile net loss to cash used in operating activities:      
Depreciation and amortization expense 49,387 29,479 18,905
Non-cash operating lease costs 19,765 0 0
Amortization of deferred contract acquisition costs 17,324 10,821 7,060
Stock-based compensation expense 56,334 36,627 27,347
Amortization of debt discount and issuance costs 21,629 0 0
Net accretion of discounts and amortization of premiums on available-for-sale securities 1,642 (1,801) (570)
Deferred income taxes (6,145) 370 385
Provision for bad debt 3,368 2,488 1,080
Change in fair value of redeemable convertible preferred stock warrant liability 0 1,517 1,220
Other 1 304 46
Changes in operating assets and liabilities, net of effect of acquisitions:      
Accounts receivable, net (33,000) (11,200) (14,758)
Contract assets (1,475) (511) 2,158
Deferred contract acquisition costs (36,315) (20,065) (12,235)
Prepaid expenses and other current assets (11,634) (7,621) (5,942)
Other noncurrent assets (2,268) (1,575) (352)
Accounts payable 1,690 (1,328) 4,386
Accrued expenses and other current liabilities 17,075 12,334 6,824
Operating lease liabilities (20,718) 0 0
Deferred revenue 25,189 14,610 4,903
Other noncurrent liabilities 392 2,462 3,426
Net cash used in operating activities (17,129) (38,917) (43,281)
Cash Flows From Investing Activities      
Purchases of property and equipment (56,375) (43,289) (25,466)
Capitalized internal-use software (18,587) (13,990) (9,373)
Cash paid for acquisitions, net of cash acquired (13,941) 0 0
Purchases of available-for-sale securities (1,267,015) (537,382) (145,269)
Sales of available-for-sale securities 0 1,978 0
Maturities of available-for-sale securities 840,248 174,998 59,249
Other investing activities 397 44 64
Net cash used in investing activities (515,273) (417,641) (120,795)
Cash Flows From Financing Activities      
Proceeds from Issuance of Redeemable Convertible Preferred Stock 0 0 149,975
Proceeds from initial public offering, net of underwriting discounts and commissions 0 570,544 0
Gross proceeds from issuance of convertible senior notes 575,000 0 0
Purchases of capped calls related to convertible senior notes (67,333) 0 0
Cash paid for issuance costs on convertible senior notes (12,542) 0 0
Proceeds from the exercise of stock options 7,457 3,058 4,412
Proceeds from the early exercise of stock options 241 2,909 14,525
Repurchases of unvested common stock (157) (283) (65)
Payments on note payable (200) (255) (356)
Proceeds from the issuance of common stock for employee stock purchase plan 10,923 0 0
Proceeds from build-to-suit lease financing obligation drawdown   63 130
Payments of deferred offering costs 0 (5,268) 0
Net cash provided by financing activities 504,912 570,768 168,621
Net increase in cash, cash equivalents, and restricted cash (27,490) 114,210 4,545
Cash, cash equivalents, and restricted cash, beginning of period 145,636 31,426 26,881
Cash, cash equivalents, and restricted cash, end of period 118,146 145,636 31,426
Supplemental Disclosure of Cash Flow Information:      
Cash paid for interest 2,192 786 786
Cash paid for income taxes, net of refunds 702 1,042 1,302
Cash paid for operating lease liabilities 20,895 0 0
Supplemental Disclosure of Non-cash Investing and Financing Activities:      
Stock-based compensation capitalized for software development 3,423 1,975 267
Accounts payable and accrued expenses related to property and equipment additions 3,052 3,571 5,757
Vesting of early exercised stock options 4,744 3,668 1,415
Deferred offering costs, accrued but not paid 0 236 0
Indemnity holdback consideration associated with business combinations 2,187 0 0
Issuance of common stock related to an acquisition 1,821 0 0
Operating lease right-of-use assets obtained in exchange for operating lease liabilities 9,893 0 0
Derecognition of build-to-suit lease 9,886 0 0
Conversion of redeemable convertible preferred stock to common stock 0 331,521 0
Conversion of redeemable convertible preferred stock warrant liability reclassified to additional paid-in capital 0 3,135 0
Restricted Stock Units (RSUs)      
Cash Flows From Financing Activities      
Payment of tax withholding obligation (8,101) 0 0
Shares issuable pursuant to the ESPP      
Cash Flows From Financing Activities      
Payment of tax withholding obligation $ (376) $ 0 $ 0
v3.20.4
Organization and Basis of Presentation
 12 Months Ended
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Organization and Basis of Presentation Organization and Basis of Presentation
Organization and Description of Business
Cloudflare, Inc. (the Company, Cloudflare, we, us, or our) has built a global network that delivers a broad range of network services to businesses of all sizes and geographies, making them more secure, enhancing the performance of their business-critical applications, and eliminating the cost and complexity of managing individual network hardware. Cloudflare provides businesses with a scalable, easy-to-use, unified control plane to deliver security, performance, and reliability across their on-premise, hybrid, cloud, and SaaS applications. The Company was incorporated in Delaware in July 2009. The Company is headquartered in San Francisco, California.
Basis of Presentation and Principles of Consolidation
The accompanying consolidated financial statements and accompanying notes have been prepared in conformity with generally accepted accounting principles in the United States (U.S. GAAP) and include the accounts of the Company and its wholly-owned subsidiaries. All intercompany balances and transactions have been eliminated in consolidation. The Company’s fiscal year ends on December 31.
Initial Public Offering
In September 2019, the Company completed an initial public offering (IPO) in which it issued and sold Class A common stock for net proceeds of $565.0 million, after deducting underwriting discounts and commissions and offering costs. Upon completion of the IPO, all of the Company's outstanding redeemable convertible preferred stock was automatically converted into Class A common stock and Class B common stock. In addition, all of the outstanding warrants to purchase shares of the Company's redeemable convertible preferred stock were automatically converted into outstanding warrants to purchase shares of Class B common stock, and all of the shares of Class B common stock held by former employees was automatically converted into Class A common stock.
Use of Estimates
The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes to the consolidated financial statements. Such estimates include, but are not limited to, allowance for doubtful accounts, deferred contract acquisitions costs, the period of benefit generated from the Company’s deferred contract acquisition costs, the capitalization and estimated useful life of internal-use software, the assessment of recoverability of intangible assets and their estimated useful lives, useful lives of property and equipment, liability and equity allocation of convertible senior notes, the determination of the incremental borrowing rate used for operating lease liabilities, the valuation and recognition of stock-based compensation expense, uncertain tax positions, and the recognition and measurement of current and deferred income tax assets and liabilities. Management bases these estimates and assumptions on historical experience and on various other assumptions that are believed to be reasonable. Due to the COVID-19 pandemic, there is ongoing uncertainty and significant disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or assumptions or a revision of the carrying value of its assets or liabilities as of February 25, 2021, the date of issuance of this Annual Report on Form 10-K. These estimates and assumptions may change in the future, however, as new events occur and additional information is obtained. Actual results could differ materially from these estimates.
v3.20.4
Summary of Significant Accounting Policies
 12 Months Ended
Dec. 31, 2020
Accounting Policies [Abstract]  
Summary of Significant Accounting Policies Summary of Significant Accounting Policies
Concentrations of Risks
The Company’s revenue is reliant on its customers utilizing Internet-based services. These services can be prone to rapid changes in technology and government regulation. If the Company were unable to keep pace with customers’ needs and continue to improve its technological capabilities, or if another firm were to introduce competitive
products, or a government jurisdiction were to enact legislation detrimental to the Company’s business, such an event or events could adversely affect the Company’s operating results.
The Company serves its customers from co-location facilities located in various cities and countries around the world. The Company has internal procedures to restore services in the event of disasters at its current co-location facilities. Even with these procedures for disaster recovery in place, the Company’s services could be significantly interrupted during the implementation of restoration procedures.
The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash, cash equivalents, available-for-sale securities, and accounts receivable. Although the Company maintains cash deposits, cash equivalent balances, and available-for-sale securities with multiple financial institutions, the deposits, at times, may exceed federally insured limits. Cash and cash equivalents may be withdrawn or redeemed on demand. The Company believes that the financial institutions that hold its cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these balances. The Company also maintains investments in U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds that carry high credit ratings and accordingly, minimal credit risk exists with respect to these balances. Cash equivalents consist of money market funds, commercial paper, and corporate bonds which are invested through financial institutions in the United States.
The Company’s accounts receivable are derived from net revenue to customers located throughout the world. The Company grants credit to its customers in the normal course of business. For the years ended December 31, 2020, 2019, and 2018, no customer accounted for more than 10% of the Company’s revenue. No customer represented 10% or more of accounts receivable, net as of December 31, 2020 and 2019.
Revenue Recognition
In accordance with ASC 606, revenue is recognized when a customer obtains control of promised services. The amount of revenue recognized reflects the consideration that the Company expects to be entitled to receive in exchange for these services. To achieve this standard, the Company applies the following five steps:
1. Identify the contract with a customer
2. Identify the performance obligations in the contract
3. Determine the transaction price
4. Allocate the transaction price to performance obligations in the contract
5. Recognize revenue when or as the Company satisfies a performance obligation
The Company generates sales directly through its sales team and through its channel partners. Revenue from sales to channel partners are recorded once all revenue recognition criteria above are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company. Payment from channel partners is not contingent on the partner’s collection from end-customers. The Company’s performance obligation primarily consists of subscription and support services, as they are provided over the same service period.
Variable Consideration
If the Company’s services do not meet certain service level commitments, its customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of these forms of variable consideration to the extent that a significant reversal of cumulative revenue will not occur in a future period. The Company has historically not experienced any incidents that had a material impact on its consolidated financial statements. Accordingly, any estimated refunds related to these agreements in the consolidated financial statements are not material during the periods presented. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s network and products in a given period and is recognized as revenue in the period in which the usage occurs.
Subscription and Support Revenue
The Company generates revenue primarily from sales to its customers of subscriptions to access its network and products, together with related support services. Arrangements with customers generally do not provide the customer with the right to take possession of the Company’s software operating its global network and products at any time. Instead, customers are granted continuous access to the Company’s global network and products over the contractual period. Access to the Company’s network and products is considered a monthly series comprising one performance obligation. A time-elapsed output method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription and support revenue is generally recognized on a straight-line basis over the contract term beginning on the date that the Company’s service is made available to the customer. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s network and products in a given period and is recognized as revenue in the period in which the usage occurs.
The subscription and support term contracts for the Company’s contracted customers, typically range from one to three years. Most of the Company’s contracts with contracted customers are non-cancelable over the contractual term. Customers typically have the right to terminate their contracts for cause, if the Company fails to perform in accordance with the contractual terms. For the Company’s pay-as-you-go customers, which consist of customers that sign up for the Company's Pro or Business subscription plans through the Company's website (and which the Company previously referred to as self-serve customers), subscription and support terms are typically monthly.
Costs to Obtain and Fulfill a Contract
The Company capitalizes sales commission and associated payroll taxes paid to internal sales personnel that are incremental to the acquisition of channel partner and direct customer contracts. These costs are recorded as deferred contract acquisition costs on the consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are in fact incremental and would not have occurred absent the customer contract.
Sales commissions for renewal of a contract are not considered commensurate with the commissions paid for the acquisition of the initial contract. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of three years while commissions paid for renewal contracts are amortized over the contractual term of the renewals. Amortization of deferred contract acquisition costs is recognized on a straight-line basis commensurate with the pattern of revenue recognition and included in sales and marketing expense in the consolidated statements of operations. The Company determines the period of benefit for commissions paid for the acquisition of the initial contract by taking into consideration the expected subscription term and expected renewals of its customer contracts, the duration of its relationships with its customers, customer retention data, its technology development lifecycle, and other factors. The Company periodically reviews the carrying amount of deferred contract acquisition costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these deferred costs.
Accounts Receivable and Allowance
Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts. Credit is extended to customers based on an evaluation of their financial condition and other factors. The Company establishes a sales allowance at the time of revenue recognition based on its history of adjustments and credits provided to customers. In determining the necessary allowance for doubtful accounts, the Company considers the current aging and financial condition of its customers, the amount of receivables in dispute, and current payment patterns. Accounts receivable are written off against the allowance when management determines a balance is uncollectible and the Company no longer actively pursues collection of the receivable. The Company does not have any off-balance-sheet credit exposure related to its customers.
Cost of Revenue
Cost of revenue consists primarily of expenses that are directly related to providing the Company's service to its paying customers. These expenses include expenses related to operating in co-location facilities, network and bandwidth costs, depreciation of the Company's equipment located in co-location facilities, certificate authority services costs for paying customers, related overhead costs, the amortization of the Company's capitalized internal-use software, and the amortization of acquired developed technologies. Cost of revenue also includes employee-related costs, including salaries, bonuses, benefits, and stock-based compensation for employees whose primary
responsibilities relate to supporting the Company's paying customers and delivering paid customer support. Other costs included in cost of revenue include credit card fees related to processing customer transactions and allocated overhead costs.
Research and Development
The Company charges costs related to research, design, and development of products to research and development expense in the consolidated statements of operations as incurred. Research and development expenses support the Company's efforts to add new features to its existing offerings and to ensure the security, performance, and reliability of its global network. The majority of the Company's research and development expenses result from employee-related costs, including salaries, bonuses and benefits, consulting costs, depreciation of equipment used in research and development, and allocated overhead costs.
Advertising Expense
Advertising costs are charged to sales and marketing expense in the consolidated statements of operations as incurred. Advertising expense for the years ended December 31, 2020, 2019, and 2018 was $25.0 million, $18.8 million, and $10.4 million, respectively.
Stock-based Compensation
The Company measures and recognizes stock-based compensation expense based on the grant date fair value of the awards. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model. The grant date fair value of restricted stock units (RSUs) is estimated based on the fair value of the Company's underlying common stock. The grant date fair value and the stock-based compensation expense related to purchase rights issued under the 2019 Employee Stock Purchase Plan (ESPP) is estimated using the Black-Scholes option pricing model and is based on the estimated number of awards as of the beginning of the offering period, respectively.
The Black-Scholes option pricing model requires the use of highly subjective assumptions, including the award’s expected term, the fair value of the underlying common stock, the expected volatility of the price of the common stock, risk-free interest rates, and the expected dividend yield of the common stock. The assumptions used to determine the fair value of the stock-based awards are management’s best estimates and involve inherent uncertainties and the application of judgment. The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. As the Company does not have sufficient historical experience for determining the expected term of the stock option awards granted, it has based its expected term on the simplified method available under U.S. GAAP. Stock-based compensation expense for awards with service-based vesting only is recognized on a straight-line basis over the requisite service period of the awards, which is generally four years. The Company accounts for forfeitures as they occur.
Prior to the IPO, the fair value of the Company's common stock for financial reporting purposes was determined considering numerous objective and subjective factors and required judgment to determine the fair value of common stock as of each grant date. Subsequent to the IPO, the Company determines the fair value using the market closing price of its Class A common stock on the date of grant.
Income Taxes
The Company accounts for income taxes using the asset and liability method. Deferred income taxes are recognized by applying the enacted statutory tax rates applicable to future years to differences between the carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The measurement of deferred tax assets is reduced, if necessary, by a valuation allowance to amounts that are more likely than not to be realized.
The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position.
Foreign Currency Remeasurement
The Company's functional currency of its foreign subsidiaries is the U.S. dollar. The monetary assets and liabilities that are denominated in a currency other than the U.S. dollar of the Company's foreign subsidiaries are remeasured into U.S. dollars at the exchange rate on the balance sheet date, while nonmonetary items are remeasured at historical rates. Revenue and expenses are remeasured at average exchange rates during the period. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations. The Company recognized remeasurement losses of $0.9 million, $0.2 million and $0.3 million for the years ended December 31, 2020 and 2019, and 2018, respectively.
Cash and Cash Equivalents
Cash and cash equivalents consist of highly liquid investments with an original maturity from the date of purchase of 90 days or less.
Available-for-sale securities
The Company’s available-for-sale securities consist of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds. The Company has designated all securities held by it as available-for-sale and therefore, such securities are reported at fair value, with unrealized gains and losses recorded in accumulated other comprehensive loss on the consolidated balance sheets. For securities sold prior to maturity, the cost of securities sold is based on the specific identification method. Realized gains and losses on the sale of available-for-sale securities are recorded in other income (expense), net in the consolidated statements of operations. All securities are classified within current assets as such securities can be liquidated to fund current operations without penalty.
Other-than-temporary impairment
All of the Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is determined to be other-than-temporary. Factors considered in determining whether a loss is temporary include the extent and length of time the investment’s fair value has been lower than its cost basis, the financial condition and near-term prospects of the investee, the extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security, and whether or not the Company will be required to sell the security prior to the expected recovery of the investment’s amortized cost basis. No such impairment charges were recorded during the years ended December 31, 2020, 2019, and 2018.
Fair Value Measurements
The carrying value of the Company’s financial instruments, including cash equivalents, available-for-sale securities, accounts receivable, accounts payable, and accrued expenses, approximates fair value due to their short-term nature.
Property and Equipment
Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows:
Useful Lives
Servers—network infrastructure4 years
Buildings30 years
Office and computer equipment3 years
Office furniture3 years
Software3 years
Leasehold improvementsLesser of useful life or term of lease
Asset retirement obligationLesser of useful life or term of lease
Expenditures for maintenance and repairs are expensed as incurred.
Capitalized Internal-Use Software Development Costs
Certain development costs related to the Company’s global network and products during the application development stage are capitalized. Costs incurred in the preliminary stages of development are analogous to research and development activities and are expensed as incurred. The preliminary stage includes such activities as conceptual formulation of alternatives, evaluation of alternatives, determination of existence of needed technology, and final selection of alternatives. Once the application development stage is reached, internal and external costs are capitalized until the software is substantially complete and ready for its intended use. Capitalized costs are recorded as part of property and equipment, net. Capitalized internal-use software is amortized on a straight-line basis over its estimated useful life, which is generally three years, and is recorded as cost of revenue in the consolidated statements of operations.
Business Combinations
The Company includes the results of operations of the businesses that the Company acquires from the date of acquisition. The fair value of the assets acquired and liabilities assumed is based on their estimated fair values as of the respective date of acquisition. The excess purchase price over the fair value of the net assets acquired and liabilities assumed is recorded as goodwill. Determining the fair value of assets acquired and liabilities assumed requires significant judgment and estimates including the selection of valuation methodologies, future expected cash flows, discount rates, and useful lives. The Company’s estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed with a corresponding offset to goodwill. At the conclusion of the measurement period, or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are reflected in the consolidated statements of operations.
When the Company issues payments or grants of equity to selling stockholders in connection with an acquisition, the Company evaluates whether the payments or awards are compensatory. This evaluation includes whether cash payments or stock award vesting is contingent on the continued employment of the selling stockholder beyond the acquisition date. If continued employment is required for the cash to be paid or stock awards to vest, the award is treated as compensation for post-acquisition services and is recognized as compensation expense.
Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expense in the Company’s consolidated statements of operations.
Convertible Senior Notes
The Company accounts for its 0.75% Convertible Senior Notes due May 2025 (the Notes) as separate liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, was calculated by deducting the fair value of the liability component from the total principal of the convertible notes. The excess of the principal amount of the liability component over its book value (debt discount) is amortized to interest expense over the term of the Notes. In accounting for the issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values. Issuance costs attributable to the liability component are being amortized over the contractual term of the Notes.
Goodwill and Intangible Assets
Goodwill represents the excess of the purchase price of an acquired business over the fair value of the net tangible and identifiable intangible assets acquired. The carrying amount of goodwill is reviewed for impairment at least annually, in the fourth quarter, or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. At December 31, 2020 and 2019, the Company had a single operating segment and reporting unit structure. As part of the annual goodwill impairment test, the Company first performs a qualitative assessment to determine whether further impairment testing is necessary. If, as a result of the qualitative assessment, it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the quantitative impairment test will be required. If the Company has determined it necessary to perform a quantitative impairment assessment,
the Company will compare the fair value of the reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the total amount of goodwill of the reporting unit. The Company did not recognize any goodwill impairment charges for any of the periods presented.
Intangible assets are carried at cost, net of accumulated amortization. Intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company estimates the useful life by estimating the expected period of economic benefit. The estimated useful life of the Company’s acquired developed technology intangible assets is two years.
Indefinite lived intangibles are assessed annually for impairment, which includes an assessment of whether there were any triggering events that required an impairment assessment of the Company’s definite lived intangible assets, and whether it was more likely than not that the Company’s indefinite lived intangible asset was impaired. The Company’s indefinite lived intangible assets arose from an asset acquisition in November 2017. As a result of acquiring assets the Company recognized $0.3 million of in-process research and development. The Company began amortizing the in-process research and development as developed technology in 2019. The Company performed an evaluation for impairment and determined there were no impairments for the years ended December 31, 2020, 2019, and 2018.
Impairment of Long-Lived Assets
The Company evaluates long-lived assets, which include depreciable tangible assets, for impairment whenever events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable. The recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows these assets are expected to generate. The Company recognizes an impairment in the event the carrying amount of such assets exceeds the fair value attributable to such assets. There were no events or changes in circumstances that indicated the long-lived assets were impaired during any of the periods presented.
Operating Leases
The Company enters into lease arrangements for real estate assets related to office space and for co-location assets related to space and equipment located in co-location facilities. The Company determines if an arrangement is, or contains, a lease at its inception by assessing whether there is an identified asset and whether the arrangement conveys the right to control the use of the identified asset in exchange for consideration for a period of time. All of the Company's leases are classified as operating leases. At lease commencement, the Company recognizes right-of-use assets, operating lease liabilities, and operating lease liabilities, noncurrent in the Company’s consolidated balance sheets, with the exception of short-term leases with an original term of 12 months or less. Right-of-use assets represent the Company's right to use an underlying asset for the lease term including any renewal options that it is reasonably certain to renew. The Company generally uses the base, non-cancelable lease term when recognizing the right-of-use assets and lease liabilities, unless it is reasonably certain that a renewal or termination option will be exercised. Operating lease liabilities represent the present value of the Company's obligation to make payments arising from the lease. Right-of-use assets are initially measured based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs incurred and (iii) tenant incentives received, incurred or payable under the lease. Right-of-use assets are periodically reviewed for impairment. Lease liabilities are initially measured at the present value of total minimum lease payments not yet paid. As the implicit rate of the Company's leases is not determinable, the Company uses an incremental borrowing rate (IBR) based on the information available at the lease commencement date in determining the present value of lease payments. Minimum lease payments consist of the fixed payments under the arrangement and variable payments that depend on an underlying index or rate, less any lease incentives such as tenant improvement allowances not yet received at commencement date. Variable lease costs that do not depend on an index or a rate are expensed as incurred and not included within the calculation of right-of-use assets and lease liabilities. The Company's operating lease arrangements contain both lease and non-lease components. At inception of an arrangement, the Company allocates the consideration to the lease and non-lease components and recognizes a right-of-use asset and corresponding lease liability for only the lease components. Lease expense for operating leases is recognized on a straight-line basis over the term of the lease.
Legal Contingencies
The Company accrues a liability for an estimated loss for legal contingencies if the potential loss from any claim or legal proceeding is considered probable, and the amount can be reasonably estimated. The Company believes there are no legal proceedings pending that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition.
Net Loss per Share Attributable to Common Stockholders
Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for multiple classes of common stock and participating securities. The Company considers its previously outstanding redeemable convertible preferred stock to be participating securities. The Company also considers any shares issued on the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have nonforfeitable dividend rights in the event a dividend is paid on common stock. Under the two-class method, net income is attributed to common stockholders and participating securities based on their participation rights. The holders of the redeemable convertible preferred stock, as well as the holders of early exercised shares subject to repurchase, do not have a contractual obligation to share in the losses of the Company. As such, the Company’s net losses for the years ended December 31, 2020, 2019, and 2018 were not allocated to these participating securities. The rights, including the liquidation and dividend rights, of the Class A common stock and Class B common stock are substantially identical, other than voting rights. Accordingly, the Class A common stock and Class B common stock share proportionately in the Company’s net losses. Prior to the completion of the IPO, there were no shares of Class A common stock issued and outstanding.
Under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase. Vested RSUs that have not been settled have been included in the appropriate common share class used to calculate basic net loss per share.
Diluted net loss per share attributable to common stockholders adjusts basic net loss per share for the effect of dilutive securities, including awards under the Company's equity incentive plans. As the Company has reported losses for all periods presented, all potentially dilutive securities are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.
Segment and Geographic Information
The Company has one reportable and operating segment. Financial information about the Company’s operating segment and geographic areas is presented in Note 15 to these consolidated financial statements.
Recent Accounting Pronouncements
Recently Adopted Accounting Pronouncements

In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842), and since that date, has issued several ASUs to further clarify certain aspects of ASU 2016-02 and provide entities with practical expedients that may be elected upon adoption. The Company adopted the new standard beginning January 1, 2020 using the modified retrospective approach, electing the optional transition approach of not adjusting the comparative period financial statements for the impact of adoption. The Company elected the package of practical expedients permitted under the transition guidance, which allows the Company to carryforward its historical lease classification, its assessment on whether a contract is or contains a lease, and its initial direct costs for any leases that existed prior to adoption of the new standard. In addition, the Company elected not to recognize lease liabilities and related right-of-use assets for leases that, at the lease commencement date, have a lease term of 12 months or less. Adoption of the new standard on January 1, 2020 resulted in the recognition of $50.0 million of operating lease right-of-use assets and $52.8 million of total operating lease liabilities on the Company's consolidated balance sheets. As part of the adoption, the Company also derecognized deferred rent of $2.8 million, primarily consisting of the noncurrent portion, net build-to-suit assets of $9.9 million, the build-to-suit lease financing obligation of $10.5 million, and recorded a cumulative-effect adjustment of $0.6 million to accumulated deficit as of January 1, 2020. Refer to Note 6 to these consolidated financial statements.
In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. This ASU changes the methodology for measuring credit losses and
requires the establishment of an allowance for estimated credit losses on financial assets, including trade and other receivables, at each reporting date. The Company adopted ASU 2016-13 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement. This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. For public business entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption of the amendments in this update is permitted, including adoption in any interim period, for all entities. The Company adopted ASU 2018-15 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842). This ASU revises, and staggers, the effective dates for various major updates that have been issued since 2014 to alleviate the burden on both larger public companies as well as private companies, smaller public companies, not-for-profit organizations, and employee benefit plans. The Company adopted ASU 2019-10 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (ASC Topic 740). This ASU simplifies accounting for income taxes by removing certain exceptions to the general principles and amending existing guidance to improve consistent application. The amendments in this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company adopted ASU 2019-12 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
Recently Issued Accounting Pronouncements
In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (ASC 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (ASC 815-40). The FASB issued this ASU to simplify the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity's own equity. The Company does not have any contracts on its own equity; however, the Company does have convertible debt. This ASU removes the separation models for 1) convertible debt with a cash conversion feature and 2) convertible instruments with a beneficial conversion feature, as well as enhances the related disclosure and earnings per share guidance. Additionally, this update requires that convertible debt be recognized as a single liability measured at its amortized cost, if no bifurcation is required, and as a result, interest expense will be closer to the coupon interest rate. For public business entities, these amendments are effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements.
v3.20.4
Revenue
 12 Months Ended
Dec. 31, 2020
Revenue from Contract with Customer [Abstract]  
Revenue Revenue
Disaggregation of Revenue
Subscription and support revenue is recognized over time and accounted for substantially all of the Company’s revenue for the years ended December 31, 2020, 2019, and 2018.
The following table summarizes the revenue by region based on the billing address of customers who have contracted to use the Company’s global network and products:
Year Ended December 31,
202020192018
(in thousands)
AmountPercentage
of Revenue		AmountPercentage
of Revenue		AmountPercentage
of Revenue
United States$218,191 51 %$144,575 50 %$92,652 48 %
Europe, Middle East, and Africa
109,274 25 %68,418 24 %48,438 25 %
Asia Pacific76,177 18 %55,131 19 %38,851 20 %
Other27,417 6 %18,898 7 %12,733 7 %
Total$431,059 100 %$287,022 100 %$192,674 100 %
The following table summarizes the revenue from contracts by type of customer:
Year Ended December 31,
202020192018
(in thousands)
AmountPercentage
of Revenue		AmountPercentage
of Revenue		AmountPercentage
of Revenue
Channel partners
$45,300 11 %$26,496 9 %$13,231 7 %
Direct customers
385,759 89 %260,526 91 %179,443 93 %
Total$431,059 100 %$287,022 100 %$192,674 100 %
Contract Balances
Contract liabilities consist of deferred revenue and include payments received in advance of performance under the contract. Such amounts are recognized as revenue over the contractual period. For the years ended December 31, 2020, 2019, and 2018 the Company recognized revenue of $31.3 million, $16.8 million, and $11.9 million, respectively, that was included in the corresponding contract liability balance at the beginning of the periods presented.
The Company receives payments from customers based upon contractual billing schedules; accounts receivable are recorded when the right to consideration becomes unconditional. Standard payment terms are due upon receipt. Contract assets include amounts related to the Company’s contractual right to consideration for both completed and partially completed performance obligations that have not been invoiced.
The following table summarizes the activity of the deferred contract acquisition costs:
Year Ended December 31,
202020192018
(in thousands)
Beginning balance$25,184 $15,940 $10,765 
Capitalization of contract acquisition costs
36,316 20,065 12,235 
Amortization of deferred contract acquisition costs
(17,324)(10,821)(7,060)
Ending balance$44,176 $25,184 $15,940 
The Company did not recognize any impairment losses of deferred contract acquisition costs during the periods presented.
Remaining Performance Obligations
As of December 31, 2020, the aggregate amount of the transaction price allocated to remaining performance obligations was $383.5 million. As of December 31, 2020, the Company expected to recognize 75% of its remaining performance obligations as revenue over the next 12 months with the remainder recognized thereafter.
v3.20.4
Fair Value Measurements
 12 Months Ended
Dec. 31, 2020
Fair Value Disclosures [Abstract]  
Fair Value Measurements Fair Value Measurements
Fair value is defined as the exchange price that would be received from sale of an asset or paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date.
Assets and liabilities measured at fair value are classified into the following categories:
•Level I: Observable inputs are unadjusted quoted prices in active markets for identical assets or liabilities;
•Level II: Observable inputs are quoted prices for similar assets and liabilities in active markets or inputs other than quoted prices that are observable for the assets or liabilities, either directly or indirectly through market corroboration, for substantially the full term of the financial instruments; and
•Level III: Unobservable inputs that are supported by little or no market activity and that are significant to the fair value of the assets or liabilities. These inputs are based on the Company’s own assumptions used to measure assets and liabilities at fair value and require significant management judgment or estimation.
The Company's cash equivalents are comprised of highly liquid money market funds and commercial paper. The Company classifies money market funds within Level I of the fair value hierarchy because they are valued based on quoted market prices in active markets. The Company classifies its investments, which are comprised of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds, within Level II of the fair value hierarchy because the fair value of these securities is priced by using inputs based on non-binding market consensus prices that are primarily corroborated by observable market data or quoted market prices for similar instruments. The Company recognizes transfers between levels within the fair value hierarchy, if any, at the end of each period. There were no transfers between levels during the periods presented.
The following table summarizes the Company’s cash and available-for-sale securities’ amortized cost, unrealized gains (losses), and fair value by significant investment category reported as cash and cash equivalents, restricted cash, or available-for-sale securities as of December 31, 2020 and 2019.
(in thousands)    Reported as:
December 31, 2020Amortized
Cost		Unrealized
Gain		Unrealized
(Loss)		Fair ValueCash & Cash EquivalentsAvailable-for-sale SecuritiesRestricted Cash
Cash$22,114 $— $— $22,114 $19,523 $— $2,591 
Level I:
Money market funds
71,038 — — 71,038 64,378 — 6,660 
Level II:
Corporate bonds
169,324 43 (26)169,341 — 169,341 — 
U.S. treasury securities
576,652 223 (4)576,871 — 576,871 — 
U.S. government agency securities
15,617 4 (1)15,620 — 15,620 — 
Commercial paper
186,363 — — 186,363 24,994 161,369 — 
Subtotal
947,956 270 (31)948,195 24,994 923,201 — 
Total assets measured at fair value on a recurring basis
$1,041,108 $270 $(31)$1,041,347 $108,895 $923,201 $9,251 

(in thousands)Reported as:
December 31, 2019Amortized
Cost		Unrealized
Gain		Unrealized
(Loss)		Fair ValueCash & Cash EquivalentsAvailable-for-sale SecuritiesLong-term Restricted Cash
Cash$24,631 $— $— $24,631 $24,631 $— $— 
Level I:
Money market funds
32,856 — — 32,856 26,196 — 6,660 
Level II:
Corporate bonds
84,054 22 (30)84,046 — 84,046 — 
U.S. treasury securities
311,083 151 (23)311,211 — 311,211 — 
U.S. government agency securities
95,380 17 — 95,397 22,549 72,848 — 
Commercial paper
95,467 — — 95,467 65,600 29,867 — 
Subtotal
585,984 190 (53)586,121 88,149 497,972 — 
Total assets measured at fair value on a recurring basis
$643,471 $190 $(53)$643,608 $138,976 $497,972 $6,660 
As of December 31, 2020 and 2019, the Company had $6.7 million in the long-term restricted cash related to irrevocable standby letters of credit established according to the requirements under lease agreements.
The aggregate fair value of the Company’s money market funds approximated amortized cost and, as such, there were no unrealized gains or losses on money market funds as of December 31, 2020 and 2019. Realized gains and losses, net of tax, were not material for any of the periods presented.
The amortized cost of available-for-sale investments with maturities less than one year was $866.5 million and $450.2 million as of December 31, 2020 and 2019, respectively. The amortized cost of available-for-sale investments with maturities greater than one year was $56.5 million and $47.7 million as of December 31, 2020 and 2019, respectively.
As of December 31, 2020, net unrealized gains on investments were $0.2 million net of tax and were included in accumulated other comprehensive income (loss) on the consolidated balance sheets. As of December 31, 2019, net unrealized gains on investments were $0.1 million net of tax and were included in accumulated other
comprehensive income (loss) on the consolidated balance sheets. The unrealized gains and losses on available-for-sale investments are related to U.S. treasury securities, U.S. government agency securities, and corporate bonds. The Company determined any unrealized losses to be temporary. Factors considered in determining whether a loss is temporary include the financial condition and near-term prospects of the investee, the extent of the loss related to the credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security, and whether or not the Company will be required to sell the security before the recovery of its amortized cost. As of December 31, 2020, the Company's investment portfolio consisted of investment grade securities with an average credit rating of AA.
The Company carries the Notes issued in May 2020 at face value less the unamortized discount and issuance costs on its consolidated balance sheets and presents that fair value for disclosure purposes only. As of December 31, 2020, the fair value of the Notes was $1,225.6 million. The fair value of the Notes, which are classified as Level II financial instruments, was determined based on the quoted bid prices of the Notes in an over-the-counter market on the last trading day of the reporting period. For further details on the Notes, refer to Note 7 to these consolidated financial statements.
The Company classifies financial instruments in Level III of the fair value hierarchy when there is reliance on at least one significant unobservable input to the valuation model. In addition to these unobservable inputs, the valuation models for Level III financial instruments typically also rely on a number of inputs that are readily observable, either directly or indirectly. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. Prior to the IPO, the Company's only Level III financial instruments were its redeemable convertible preferred stock warrants. Upon the completion of the IPO, the warrant to purchase shares of redeemable convertible preferred stock was converted into a warrant to purchase shares of Class B common stock. As a result, the warrant liability was remeasured and reclassified to additional paid-in capital within stockholders' equity (deficit). There were no financial instruments classified as Level III of the fair value hierarchy as of December 31, 2020 and December 31, 2019.
v3.20.4
Balance Sheet Components
 12 Months Ended
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Balance Sheet Components Balance Sheet Components
Accounts Receivable, Net
Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts.
Activity in the allowance for doubtful accounts was as follows:
December 31,
202020192018
(in thousands)
Beginning balance$533 $160 $— 
Provision for bad debt3,368 2,488 1,080 
Write-off of uncollectible accounts receivable(2,198)(2,115)(920)
Ending balance$1,703 $533 $160 
Prepaid Expenses and Other Current Assets
Prepaid expenses and other current assets consisted of the following:
 December 31,
20202019
 (in thousands)
Prepaid expenses$13,689 $10,913 
Deposits4,246 2,773 
Other10,295 3,308 
Total prepaid expenses and other current assets$28,230 $16,994 
Property and Equipment, Net
Property and equipment, net consisted of the following:
December 31,
20202019
(in thousands)
Property and equipment:
Servers—network infrastructure$108,988 $84,979 
Buildings— 13,035 
Construction in progress11,242 8,692 
Capitalized internal-use software49,618 31,171 
Office and computer equipment17,867 13,528 
Office furniture5,657 6,124 
Software1,808 1,025 
Leasehold improvements10,686 9,870 
Asset retirement obligation430 231 
Gross property and equipment206,296 168,655 
Less accumulated depreciation and amortization(82,608)(67,189)
Total property and equipment, net$123,688 $101,466 
In connection with the adoption of ASC 842, the Company derecognized the building asset of $13.0 million as of January 1, 2020, which was initially recorded as a result of build-to-suit lease accounting and reclassified a portion of the balance, $1.6 million, to leasehold improvements. This amount reflects the lessee-owned assets of the construction project and is being depreciated over the remaining lease term. For further details on the adoption of ASC 842, refer to Note 2 to these consolidated financial statements.
Depreciation and amortization expense on property and equipment for the years ended December 31, 2020, 2019, and 2018 was $45.9 million, $29.4 million, and $18.4 million, respectively. This includes amortization expense for capitalized internal-use software which totaled $12.6 million, $6.7 million, and $3.3 million for the years ended December 31, 2020, 2019, and 2018, respectively.
Goodwill
As of December 31, 2020 and 2019, the Company's goodwill was $17.2 million and $4.1 million, respectively. During the year ended December 31, 2020, the Company recorded $13.1 million of goodwill in connection with the acquisition of S2 Systems Corporation (S2). For further detail on the acquisition, refer to Note 14 to these consolidated financial statements. No goodwill impairments were recorded during the years ended December 31, 2020 and 2019.
Acquired Intangible Assets, Net
Acquired intangible assets, net consisted of the following:
December 31, 2020
Gross Carrying
Amount		Accumulated
Amortization		Net Book
Value
(in thousands)
Developed technology$5,600 $2,800 $2,800 
Total acquired intangible assets, net$5,600 $2,800 $2,800 

December 31, 2019
Gross Carrying
Amount		Accumulated
Amortization		Net Book
Value
(in thousands)
Developed technology$250 $219 $31 
Total acquired intangible assets, net$250 $219 $31 
The Company recorded $5.6 million of developed technology in connection with the acquisition of S2 as of December 31, 2020. For further details on the acquisition, refer to Note 14 of these consolidated financial statements.
Amortization of acquired intangible assets for the years ended December 31, 2020, 2019, and 2018 was $3.1 million, $0.1 million, and $0.5 million, respectively.
As of December 31, 2020, the estimated future amortization expense of acquired intangible assets was as follows:
Estimated
Amortization
(in thousands)
Year ending December 31,
2021$2,800 
Total$2,800 
Accrued Expenses and Other Current Liabilities
Accrued expenses and other current liabilities consisted of the following:
December 31,
20202019
(in thousands)
Accrued compensation and benefits$25,410 $14,970 
Accrued expenses6,916 5,331 
Customer refunds and credits1,548 3,328 
Accrued co-location and bandwidth5,205 2,696 
Other6,548 1,989 
Total accrued expenses and other current liabilities$45,627 $28,314 
Other Noncurrent Liabilities
Other noncurrent liabilities consisted of the following:
December 31,
20202019
(in thousands)
Accrued taxes$7,033 $4,862 
Deferred rent— 2,342 
Other2,826 2,599 
Total other noncurrent liabilities$9,859 $9,803 

In connection with the adoption of ASC 842, the Company derecognized the deferred rent as of January 1, 2020. For further details on the adoption of ASC 842, refer to Note 2 to these consolidated financial statements.
v3.20.4
Leases
 12 Months Ended
Dec. 31, 2020
Leases [Abstract]  
Leases Leases
The Company's lease portfolio consists of real estate and co-location agreements in the U.S. and internationally. The real estate leases include leases for office space and have remaining lease terms of up to 4.0 years. Certain of these leases contain options that allow the Company to extend or terminate the lease agreement. The Company's co-location leases have remaining lease terms of up to 5.6 years. All of the Company's leases are classified as operating leases.
The Company also subleases one of its leased office spaces. The sublease has a remaining lease term of 0.4 years. Sublease income, which is recorded as a reduction of rent expense was $2.8 million and $1.6 million for the years ended December 31, 2020 and 2019, respectively.
The components of lease cost related to the Company's operating leases included in the consolidated statements of operations were as follows:
Year Ended December 31,
2020
(in thousands)
Operating lease cost$19,544 
Sublease income(2,829)
Total lease cost$16,715 
Variable lease cost and short-term lease cost for the year ended December 31, 2020 were not material.
As of December 31, 2020, the Company had $15.4 million of total undiscounted future payments under operating leases that have not yet commenced, which were not included on the consolidated balance sheets. These operating leases will commence between January 2021 and October 2024 and have an average lease term of 3.5 years.
As of December 31, 2020, the weighted-average remaining term of the Company’s operating leases was 2.8 years and the weighted-average discount rate used to measure the present value of the operating lease liabilities was 3.1%.

Maturities of the operating lease liabilities as of December 31, 2020 are as follows:
December 31, 2020
(in thousands)
2021$18,750 
202214,784 
20238,357 
20244,552 
2025557 
Thereafter92 
Total lease payments$47,092 
Less: Imputed interest$(2,066)
Total operating lease liabilities$45,026 
Prior to the Company's adoption of ASC 842, future minimum operating lease payments as of December 31, 2019 were as follows:
December 31, 2019
(in thousands)
2020$18,618 
202116,942 
202212,423 
20236,410 
20244,474 
Thereafter10,304 
Total lease payments$69,171 
The amounts above include the build-to-suit lease.
Prior to the Company's adoption of ASC 842, the Company recognized rent expense on a straight-line basis over the lease period. The difference between the rent paid and the straight-line rent was recorded as deferred rent, which was included in accrued expenses and other current liabilities and other noncurrent liabilities on the consolidated balance sheets. Rent expense was $11.2 million for the year ended December 31, 2019.
Leases Leases
The Company's lease portfolio consists of real estate and co-location agreements in the U.S. and internationally. The real estate leases include leases for office space and have remaining lease terms of up to 4.0 years. Certain of these leases contain options that allow the Company to extend or terminate the lease agreement. The Company's co-location leases have remaining lease terms of up to 5.6 years. All of the Company's leases are classified as operating leases.
The Company also subleases one of its leased office spaces. The sublease has a remaining lease term of 0.4 years. Sublease income, which is recorded as a reduction of rent expense was $2.8 million and $1.6 million for the years ended December 31, 2020 and 2019, respectively.
The components of lease cost related to the Company's operating leases included in the consolidated statements of operations were as follows:
Year Ended December 31,
2020
(in thousands)
Operating lease cost$19,544 
Sublease income(2,829)
Total lease cost$16,715 
Variable lease cost and short-term lease cost for the year ended December 31, 2020 were not material.
As of December 31, 2020, the Company had $15.4 million of total undiscounted future payments under operating leases that have not yet commenced, which were not included on the consolidated balance sheets. These operating leases will commence between January 2021 and October 2024 and have an average lease term of 3.5 years.
As of December 31, 2020, the weighted-average remaining term of the Company’s operating leases was 2.8 years and the weighted-average discount rate used to measure the present value of the operating lease liabilities was 3.1%.

Maturities of the operating lease liabilities as of December 31, 2020 are as follows:
December 31, 2020
(in thousands)
2021$18,750 
202214,784 
20238,357 
20244,552 
2025557 
Thereafter92 
Total lease payments$47,092 
Less: Imputed interest$(2,066)
Total operating lease liabilities$45,026 
Prior to the Company's adoption of ASC 842, future minimum operating lease payments as of December 31, 2019 were as follows:
December 31, 2019
(in thousands)
2020$18,618 
202116,942 
202212,423 
20236,410 
20244,474 
Thereafter10,304 
Total lease payments$69,171 
The amounts above include the build-to-suit lease.
Prior to the Company's adoption of ASC 842, the Company recognized rent expense on a straight-line basis over the lease period. The difference between the rent paid and the straight-line rent was recorded as deferred rent, which was included in accrued expenses and other current liabilities and other noncurrent liabilities on the consolidated balance sheets. Rent expense was $11.2 million for the year ended December 31, 2019.
v3.20.4
Debt
 12 Months Ended
Dec. 31, 2020
Debt Disclosure [Abstract]  
Debt Debt
Convertible Senior Notes
In May 2020, the Company issued $575.0 million aggregate principal amount of the Notes in a private offering to qualified institutional buyers pursuant to Rule 144A promulgated under the Securities Act, including the initial purchasers' exercise in full of their option to purchase an additional $75.0 million aggregate principal amount of the Notes. The total net proceeds from the issuance of the Notes, after deducting initial purchaser discounts and debt issuance costs, were $562.5 million.
The Notes are senior unsecured obligations of the Company and will mature on May 15, 2025, unless earlier redeemed, repurchased, or converted, and are governed by the terms of the Indenture dated May 15, 2020 (the Indenture). Interest is payable semi-annually in arrears on May 15 and November 15 of each year, beginning on November 15, 2020, at a rate of 0.75% per year.
The Notes are convertible at an initial conversion rate of 26.7187 shares of the Company's Class A common stock per $1,000 principal amount of the Notes, which is equivalent to an initial conversion price of approximately $37.43 per share, subject to adjustment upon the occurrence of specified events. The Notes may be converted at any time on or after February 15, 2025 until the close of business on the second scheduled trading day immediately preceding the maturity date. Holders of the Notes may convert all or any portion of their Notes at their option at any
time prior to the close of business on the business day immediately preceding February 15, 2025 only under the following circumstances:
(1) during any calendar quarter commencing after the calendar quarter ending on September 30, 2020 (and only during such calendar quarter), if the last reported sale price of the Company's Class A common stock for at least 20 trading days (whether or not consecutive) during a period of 30 consecutive trading days ending on, and including, the last trading day of the immediately preceding calendar quarter is greater than or equal to 130% of the conversion price on each applicable trading day;
(2) during the five business day period after any five consecutive trading day period in which the trading price per $1,000 principal amount of the Notes for each trading day of the measurement period was less than 98% of the product of the last reported sale price of the Company's Class A common stock and the conversion rate on each such trading day;
(3) if the Company calls such Notes for redemption, at any time prior to the close of business on the second scheduled trading day immediately preceding the redemption date; or
(4) upon the occurrence of specified corporate events.
In addition, if the Notes are converted prior to the maturity date following certain specified corporate events or because the Company issues a notice of redemption, the Company will increase the conversion rate for such Notes converted in connection with such a corporate event or during the related redemption period, as the case may be, in certain circumstances.
The circumstances described in (1) above were met during the fourth calendar quarter of 2020 and, as a result, the Notes are convertible at the option of the holder from January 1, 2021 and remain convertible until March 31, 2021.
Upon conversion, the Company will pay or deliver, as the case may be, cash, shares of the Company's Class A common stock, or a combination of cash and shares of the Company's Class A common stock, at the Company's election. It is the Company’s current intent to settle the principal amount of Notes with cash.
The Company may not redeem the Notes prior to May 20, 2023. The Company may redeem for cash all or any portion of the Notes, at its option, on or after May 20, 2023, if the last reported sale price of the Company’s Class A common stock has been at least 130% of the conversion price then in effect for at least 20 trading days (whether or not consecutive) during any 30 consecutive trading day period (including the last trading day of such period) ending on, and including, the trading day preceding the date on which the Company provides notice of redemption at a redemption price equal to 100% of the principal amount of the Notes to be redeemed, plus any accrued and unpaid interest to, but excluding, the redemption date. No sinking fund is provided for the Notes.
If the Company undergoes a fundamental change (as defined in the Indenture), holders of the Notes may require the Company to repurchase for cash all or any portion of their notes at a fundamental change repurchase price equal to 100% of the principal amount of the Notes to be repurchased, plus accrued and unpaid interest to, but excluding, the fundamental change repurchase date.
In accounting for the issuance of the Notes, the Company separated the Notes into liability and equity components. The carrying amount of the liability component was calculated by using an effective interest rate of 10.0%, which was determined by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component representing the conversion option and recorded in additional paid-in capital was $205.3 million and was determined by deducting the fair value of the liability component from the par value of the Notes. The equity component is not remeasured as long as it continues to meet the conditions for equity classification. The excess of the principal amount of the liability component over its carrying amount represents a debt discount that is amortized to interest expense over the contractual term of the Notes.
In accounting for the issuance costs related to the Notes, the Company allocated the total amount incurred to the liability and equity components based on the proportion of the proceeds allocated to the debt and equity components. Issuance costs attributable to the liability component were $8.0 million (presented as a reduction to the carrying amount of debt) and are being amortized to interest expense over the contractual term of the Notes. The issuance costs attributable to the equity component were $4.5 million and are netted against the equity component in additional paid-in capital.
The net carrying amount of the liability component of the Notes was as follows:

December 31, 2020
(in thousands)
Principal$575,000 
Unamortized debt discount(184,674)
Unamortized debt issuance costs(7,051)
Carrying amount of the liability component, net$383,275 

The net carrying amount of the equity component of the Notes was as follows:
December 31, 2020
(in thousands)
Proceeds allocated to the conversion option (debt discount)$205,290 
Less: allocated issuance costs(4,478)
Carrying amount of the equity component, net$200,812 

Based on the closing price of the Company's common stock of $75.99 on December 31, 2020, the if-converted value of the Notes exceeded its principal amount by approximately $592.5 million. The remaining life of the Notes was approximately 53 months.

The following table sets forth total interest expense recognized related to the Notes:
Year Ended December 31,
2020
(in thousands)
Coupon interest expense$2,707 
Amortization of debt discount20,616 
Amortization of debt issuance costs1,013 
Total$24,336 

Capped Call Transactions
In connection with the offering of the Notes, the Company entered into privately-negotiated capped call transactions with certain financial institution counterparties (the Capped Calls). The Capped Calls each have an initial strike price of approximately $37.43 per share of the Company's Class A common stock, subject to certain adjustments, which corresponds to the initial conversion price of the Notes. The Capped Calls each have an initial cap price of approximately $57.58 per share, subject to certain adjustments. The Capped Calls initially cover, subject to anti-dilution adjustments, approximately 15.4 million shares of the Company's Class A common stock. The Capped Calls are intended to generally offset potential dilution to the Company's Class A common stock upon conversion of the Notes and/or offset the potential cash payments that the Company could be required to make in excess of the principal amount upon any conversion, subject to the cap price. The Capped Calls are subject to either adjustment or termination upon the occurrence of certain specified events affecting the Company, including a merger event, a tender offer, and a nationalization, insolvency, or delisting involving the Company. The Capped Calls expire in incremental components on each trading date between March 18, 2025 and May 13, 2025.
The Capped Calls are recorded in stockholders' equity and are not accounted for as derivatives. The premium paid for the purchase of the Capped Calls of $67.3 million was recorded as a reduction to additional paid-in capital on the consolidated balance sheets.
v3.20.4
Commitments and Contingencies
 12 Months Ended
Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]  
Commitments and Contingencies Commitments and Contingencies
Purchase Commitments
Open purchase commitments are for the purchase of services under non-cancelable contracts. They are not recorded as liabilities on the consolidated balance sheet as of December 31, 2020 as the Company has not yet received the related services. Refer to the table below for purchase commitments under non-cancelable contracts with various vendors as of December 31, 2020.
Bandwidth & Co-location Commitments
The Company enters into long-term non-cancelable agreements with providers in various countries to purchase capacity, such as bandwidth and co-location space, for the Company’s global network. Bandwidth and co-location costs for paying customers are recorded as cost of revenue in the consolidated statements of operations and as sales and marketing expense in the consolidated statements of operations for free customers. Such costs totaled $51.4 million, $37.0 million, and $27.5 million for the years ended December 31, 2020, 2019, and 2018, respectively. Refer to the table below for long-term bandwidth and co-location commitments under non-cancelable contracts with various networks and Internet service providers as of December 31, 2020. For the lease components of co-location agreements, refer to Note 6 to these consolidated financial statements.

Payments Due by Period as of December 31, 2020
Total20212022202320242025Thereafter
(in thousands)
Non-cancelable:
Open purchase agreements(1)
$17,621 $5,360 $4,626 $1,866 $741 $752 $4,276 
Bandwidth and other co-location related commitments(2)
36,797 14,420 11,769 5,294 2,194 2,086 1,034 
Other commitments(3)
2,187 2,187 — — — — — 
Total$56,605 $21,967 $16,395 $7,160 $2,935 $2,838 $5,310 
(1)Open purchase commitments are for the purchase of services under non-cancelable contracts. They were not recorded as liabilities on the consolidated balance sheet as of December 31, 2020 as the Company had not yet received the related services.
(2)Long-term commitments for bandwidth usage and other co-location related commitments with various networks and Internet service providers. The costs for services not yet received were not recorded as liabilities on the consolidated balance sheet as of December 31, 2020.
(3)Indemnity holdback consideration associated with the S2 acquisition. See Note 14.
Legal Matters
From time to time the Company is a party to various legal proceedings that arise in the ordinary course of business. In addition, third parties may from time to time assert claims against the Company in the form of letters and other communications. Management currently believes that there is no pending or threatened legal proceeding to which the Company is a party that is likely to have a material adverse effect on the Company’s consolidated financial statements. However, the results of legal proceedings are inherently unpredictable and if an unfavorable ruling were to occur in any of the legal proceedings there exists the possibility of a material adverse effect on the Company’s financial position, results of operations, and cash flows. The Company accrues for legal proceedings that it considers probable and for which the loss can be reasonably estimated. The Company also discloses material contingencies when it believes a loss is not probable but reasonably possible. Legal costs incurred and expected to be incurred related to litigation matters are expensed as incurred.
The Company’s network and associated products are subject to various restrictions under U.S. export control and sanctions laws and regulations, including the U.S. Department of Commerce’s Export Administration Regulations (EAR) and various economic and trade sanctions regulations administered by the U.S. Department of the Treasury’s Office of Foreign Assets Controls (OFAC). The U.S. export control laws and U.S. economic sanctions laws include restrictions or prohibitions on the sale or supply of certain products and services to U.S. embargoed or sanctioned countries, governments, persons and entities and also require authorization for the export of certain encryption
items. In addition, various countries regulate the import of certain encryption technology, including through import permitting and licensing requirements and have enacted or could enact laws that could limit the Company’s ability to distribute its products.
Although the Company takes precautions to prevent its network and associated products from being accessed or used in violation of such laws, the Company may have inadvertently allowed its network and associated products to be accessed or used by some customers in apparent violation of U.S. economic sanctions laws, including by users in embargoed or sanctioned countries, and the Company may have exported or allowed the download of certain software prior to making required filings with the U.S. Department of Commerce’s Bureau of Industry and Security. As a result, the Company has submitted to OFAC and to the Bureau of Industry and Security a voluntary self-disclosure concerning potential violations, and the Company has submitted a voluntary self-disclosure to the Census Bureau regarding potential violations of the Foreign Trade Regulations related to some incorrect electronic export information statements to the U.S. government for certain hardware exports, which were authorized. The voluntary self-disclosure to the Census Bureau was completed with no penalties in November 2019, and the voluntary self-disclosure to the Bureau of Industry and Security was completed with no penalties in June 2020. The voluntary self-disclosure to OFAC remains under review. If the Company is found to be in violation of U.S. economic sanctions or export control laws, it could result in substantial fines and penalties for the Company and for the individuals working for the Company. The Company may also be adversely affected through other penalties, reputational harm, loss of access to certain markets or otherwise. No loss has been recognized in the consolidated financial statements for this loss contingency as it is not probable a loss has been incurred and the range of a possible loss is not yet estimable.
Guarantees and Indemnifications
If the Company's services do not meet certain service level commitments, its contracted customers and certain of its pay-as-you-go customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. To date, the Company has not incurred any material costs as a result of such commitments.
The Company’s arrangements generally include certain provisions for indemnifying customers against liabilities if its products or services infringe a third-party’s intellectual property rights. It is not possible to determine the maximum potential amount under these indemnification obligations due to the limited history of prior indemnification claims and the unique facts and circumstances involved in each particular agreement. To date, the Company has not incurred any material costs as a result of such obligations and has not accrued any liabilities related to such obligations in the consolidated financial statements.
The Company has also agreed to indemnify its directors, executive officers, and certain other employees for costs associated with any fees, expenses, judgments, fines, and settlement amounts incurred by them in any action or proceeding to which any of them are, or are threatened to be, made a party by reason of their service as a director or officer. The Company maintains director and officer insurance coverage that would generally enable it to recover a portion of any future amounts paid. The Company also may be subject to indemnification obligations by law with respect to the actions of its employees under certain circumstances and in certain jurisdictions.
v3.20.4
Preferred Stock
 12 Months Ended
Dec. 31, 2020
Equity [Abstract]  
Preferred Stock Preferred StockIn connection with the IPO, the Company's amended and restated certificate of incorporation became effective, which authorized the issuance of 225,000,000 shares of preferred stock with a par value of $0.001 per share with rights and preferences, including voting rights, designated from time to time by the Company's Board of Directors.
v3.20.4
Common Stock
 12 Months Ended
Dec. 31, 2020
Equity [Abstract]  
Common Stock Common StockThe Company’s amended and restated certificate of incorporation authorizes the issuance of Class A common stock and Class B common stock. The holder of each share of Class A common stock is entitled to one vote per share, while the holder of each share of Class B common stock is entitled to 10 votes per share. As of December 31, 2020 and 2019, the Company was authorized to issue 2,250,000,000 shares of Class A common stock and 315,000,000 shares of Class B common stock, each with a par value of $0.001 per share. There were 249,401,232
and 87,071,783 shares of Class A common stock issued and outstanding as of December 31, 2020 and 2019, respectively. The number of shares of Class B common stock issued and outstanding was 59,238,742 and 213,101,364, as of December 31, 2020 and 2019, respectively.
Holders of the Company’s Class A common stock and Class B common stock are entitled to dividends when, as and if, declared by the Company’s Board of Directors, subject to the rights of the holders of all classes of stock outstanding having priority rights to dividends. Any dividends paid to the holders of the Class A common stock and Class B common stock will be paid on a pro rata basis. As of December 31, 2020 and 2019, the Company had not declared any dividends. The rights of the holders of Class A and Class B common stock are identical, except with respect to voting and conversion. Shares of the Company's Class B common stock are convertible into an equivalent number of shares of the Company's Class A common stock and generally convert into shares of the Company's Class A common stock upon cessation of employment or transfer, except for certain transfers described in the Company's amended and restated certificate of incorporation. Class A common stock and Class B common stock are referred to, collectively, as common stock throughout the notes to these consolidated financial statements, unless otherwise indicated.
Common Stock Reserved for Future Issuance
Shares of common stock reserved for future issuance, on an as-if converted basis, are as follows:
December 31,
20202019
(in thousands)
Convertible senior notes19,972 — 
Stock options issued and outstanding18,186 21,191 
Remaining shares available for issuance under the 2019 Plan24,539 29,048 
Outstanding and unsettled restricted stock units (RSUs)7,808 7,175 
Shares available for issuance under the ESPP5,230 5,870 
Total shares of common stock reserved75,735 63,284 
v3.20.4
Stock-based Compensation
 12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Stock-based Compensation Stock-based Compensation
Equity Incentive Plans
In 2010, the Company's Board of Directors adopted and stockholders approved the 2010 Equity Incentive Plan (2010 Plan). The 2010 Plan is a broad-based retention program and is intended to attract and retain talented employees, directors, and non-employee consultants. The 2010 Plan provides for the granting of stock options, restricted stock, RSUs, and stock appreciation rights to employees, directors, and consultants. Incentive stock options may be granted only to employees. All other awards under the 2010 Plan, including non-qualified stock options, may be granted to employees, directors, and consultants. Except for qualifying assumptions and substitutions of options, the exercise price of an incentive stock option and non-qualified stock option shall not be less than 100% of the fair market value of such shares on the date of grant. Prior to the Company's IPO, stock-based awards forfeited, canceled, or repurchased generally were returned to the pool of shares of common stock available for issuance under the 2010 Plan. In connection with the IPO, the 2010 Plan was terminated effective immediately prior to the effectiveness of the 2019 Equity Incentive Plan (2019 Plan) and the Company ceased granting any additional awards under the 2010 Plan. All outstanding awards under the 2010 Plan at the time of the termination of the 2010 Plan remain subject to the terms of the 2010 Plan, and any shares underlying stock options that expire or terminate or are forfeited or repurchased by the Company under the 2010 Plan will be automatically transferred to the 2019 Plan.
In 2019, the Company's Board of Directors adopted and stockholders approved the 2019 Plan, which became effective one business day prior to the effective date of the Company's registration statement on Form S-1 for the IPO. The 2019 Plan provides for the granting of stock options, restricted stock, RSUs, stock appreciation rights, performance shares, performance stock units, and performance awards for the Company's Class A common stock to the Company's employees, directors, and consultants. Except as otherwise indicated below, the maximum number of shares of Class A common stock that may be issued under the 2019 Plan will not exceed 66,661,953
shares of the Company's Class A common stock, which is the sum of (1) 29,335,000 new shares, plus (2) an additional number of shares of Class A common stock not to exceed 37,326,953, consisting of the total number of shares of Class A or Class B common stock subject to outstanding awards granted under the 2010 Plan that, on or after the 2019 Plan became effective, are canceled, expire, or otherwise terminate prior to exercise or settlement; are repurchased by the Company because of the failure to vest; or are forfeited, tendered to, or withheld by the Company (or not issued) to satisfy a tax withholding obligation or the payment of an exercise price, if any, as such shares become available from time to time. Stock-based awards under the 2019 Plan that expire or are forfeited, canceled, or repurchased generally are returned to the pool of shares of Class A common stock available for issuance under the 2019 Plan. In addition, the number of shares of the Company's Class A common stock reserved for issuance under the 2019 Plan will automatically increase on January 1 of each calendar year, starting on January 1, 2021 through January 1, 2029, in an amount equal to the least of (i) 29,335,000 shares, (ii) 5% of the total number of shares of Class A and Class B common stock outstanding on December 31 of the fiscal year before the date of each automatic increase, or (iii) a lesser number of shares determined by the compensation committee of the Company's Board of Directors prior to the applicable January 1. As of December 31, 2020, 1,710,189 stock options to purchase shares of Class A common stock and 4,152,972 shares of Class A common stock underlying RSUs have been granted under the 2019 Plan, and the number of shares of Class A common stock available for issuance under the 2019 Plan was 24,538,422.
Stock Options
Under the 2010 Plan and 2019 Plan, at exercise, stock option awards entitle the holder to receive one share of Class B or Class A common stock, in the case of the 2010 Plan, or one share of Class A common stock, in the case of the 2019 Plan. Stock options granted under the 2010 Plan and the 2019 Plan generally vest over a four-year period subject to remaining continuously employed and expire no more than 10 years from the date of grant.
The following table summarizes the stock options activity under the 2010 Plan and 2019 Plan:
Stock Options Outstanding
(in thousands, except year and per share data)
Shares Subject
to Options
Outstanding		Weighted-
Average
Exercise Price
per Option		Weighted-
Average
Remaining
Contractual
Terms (in years)		Aggregate
Intrinsic Value
Balances as of December 31, 201728,127 $1.62 8.5$11,684 
Options granted10,527 $2.91 
Options exercised(12,387)$1.53 $15,433 
Repurchase of unvested shares— 
Options canceled/forfeited/expired(1,180)$2.24 
Balances as of December 31, 201825,087 $2.18 8.4$159,945 
Options granted394 $9.60 
Options exercised(2,665)$2.24 $22,306 
Repurchase of unvested shares— 
Options canceled/forfeited/expired(1,625)$2.35 
Balances as of December 31, 201921,191 $2.30 7.4$312,720 
Options granted 1,710 $18.05 
Options exercised (4,451)$1.73 $142,758 
Repurchase of unvested shares
Options canceled/forfeited/expired (264)$2.61 
Balances as of December 31, 202018,186 $3.92 7.0$1,310,650 
Vested and expected to vest as of December 31, 202018,186 $3.92 7.0$1,310,650 
Exercisable as of December 31, 202016,482 $2.47 6.8$1,211,809 
The weighted-average assumptions used to determine the fair value of stock options granted during the periods presented were as follows:
Year ended December 31,
202020192018
Expected term (in years)6.06.26.5
Expected volatility40.3 %40.3 %43.5 %
Risk-free interest rate0.7 %2.3 %2.9 %
Dividend yield— — — 
The weighted-average grant date fair value of options granted during the years ended December 31, 2020, 2019, and 2018 was $9.74, $4.10, and $1.38 per share, respectively.
The aggregate intrinsic value is the difference between the exercise price of the option and the estimated fair value of the underlying common stock. Options exercisable include 10,765,894 and 15,477,903 options that were unvested as of December 31, 2020 and 2019, respectively.
The total grant date fair value for vested options in the years ended December 31, 2020, 2019, and 2018 was $7.3 million, $5.2 million, and $3.4 million, respectively.
As of December 31, 2020 and 2019, there was $20.6 million and $15.8 million, respectively, of unrecognized stock-based compensation expense related to unvested stock options that is expected to be recognized over a weighted-average period of 2.6 years and 2.7 years, respectively.
Early Exercises of Stock Options
The 2010 Plan allows for the early exercise of stock options for certain individuals as determined by the Company’s Board of Directors. Shares of common stock issued upon early exercises of unvested options are not deemed, for accounting purposes, to be issued until those shares vest according to their respective vesting schedules and accordingly, the consideration received for early exercises is initially recorded as a liability and reclassified to common stock and additional paid-in capital as the underlying awards vest. Stock options that are early exercised are subject to a repurchase option that allows the Company to repurchase within six months of an individual’s termination for any reason, including death and disability (or in the case of shares issued upon exercise of an option after termination, within six months of the date of exercise), any unvested shares of such individual for a repurchase price equal to the amount previously paid by the individual for such unvested shares. As of December 31, 2020 and 2019, the Company had $8.6 million and $13.3 million, respectively, recorded in liability for early exercise of unvested stock options, and the related number of unvested shares subject to repurchase was 3,871,772 and 5,945,083, respectively.
Restricted Stock and Restricted Stock Units
RSUs granted under the 2010 Plan generally vest upon the satisfaction of both a service-based vesting condition and a performance vesting condition, as defined below, occurring before these RSUs expire. RSUs granted under the 2019 Plan generally vest upon the satisfaction of a service-based vesting condition. The service-based vesting condition for employees under both the 2010 Plan and the 2019 Plan is typically satisfied over a four-year period, subject to remaining continuously employed. The performance vesting condition under the 2010 Plan was deemed satisfied upon the effective date of the Company's registration statement on Form S-1 filed with the SEC in connection with the IPO.
In connection with the acquisition of S2, the Company issued 948,000 shares of Class A common stock to former S2 shareholders, some of which have joined the Company as employees. Of these issued shares, 841,000 shares are restricted stock that is subject to vesting, with 77.8% of this restricted stock vesting in two years from the acquisition date and the remainder of this restricted stock vesting in three years from the acquisition date, in each case subject to remaining continuously employed. The total grant date fair value for vested shares in the year ended December 31, 2020 and 2019, was $1.8 million and zero, respectively. The total stock-based compensation expense for shares of unvested restricted stock for the year ended December 31, 2020 and 2019 was $5.6 million and zero, respectively. As of December 31, 2020 and 2019, the total unrecognized stock-based compensation expense related to unvested restricted stock was $8.8 million and zero, respectively. For further details on the S2 acquisition, refer to Note 14 to these consolidated financial statements.
RSU activity for the year ended December 31, 2020 was as follows:
Restricted Stock and RSUsWeighted-Average
Grant
Date Fair Value
(in thousands, except per share data)
Unvested and outstanding as of December 31, 20196,508 $11.08 
Granted - RSUs4,153 $33.13 
Granted - Restricted stock949 $17.06 
Vested - RSUs(2,286)$11.80 
Vested - Restricted stock(107)$17.06 
Forfeited (588)$13.18 
Unvested as of December 31, 20208,629 $21.38 
Vested and not yet released21 $36.56 
Outstanding as of December 31, 20208,650 $21.41 
The total grant date fair value for vested RSUs were $27.0 million, $6.0 million, and zero for the years ended December 31, 2020, 2019 and 2018, respectively. The total stock-based compensation expense for RSUs were $39.6 million, $24.9 million, and zero for the years ended December 31, 2020, 2019 and 2018, respectively. As of December 31, 2020 and 2019, the total unrecognized stock-based compensation expense related to RSUs was $141.8 million and $53.1 million, respectively, that is expected to be recognized over a weighted-average period of 3.5 years and 2.5 years, respectively.
2019 Employee Stock Purchase Plan
In September 2019, the Company's Board of Directors adopted and stockholders approved the 2019 Employee Stock Purchase Plan (ESPP), which became effective one business day prior to the effective date of the Company's registration statement on Form S-1 filed with the SEC in connection with the IPO. A total of 5,870,000 shares of Class A common stock were initially reserved for sale under the ESPP. The number of shares of Class A common stock reserved for issuance includes an annual increase on the first day of each fiscal year, beginning on January 1, 2021, by the least of (1) 5,870,000 shares of Class A common stock, (2) 1% of the total number of shares of Class A and Class B common stock outstanding on December 31 of the fiscal year before the date of each automatic increase; or (3) such lesser amount as the compensation committee of the Company's Board of Directors may determine prior to the applicable January 1.
Generally, all regular employees, including executive officers, employed by the Company or by any of its designated subsidiaries, except for those holding 5% or more of the total combined voting power or value of all classes of common stock, may participate in the ESPP and may contribute, normally through payroll deductions, up to 10% of their eligible compensation for the purchase of Class A common stock under the ESPP. Unless otherwise determined by the compensation committee of the Board of Directors, Class A common stock will be purchased for the accounts of employees participating in the ESPP at a price per share that is the lesser of (1) 85% of the fair market value of a share of the Company's Class A common stock on the first date of an offering period, or (2) 85% of the fair market value of a share of the Company's Class A common stock on the date of purchase.
The ESPP generally provides for six-month offering periods beginning on the first day of trading on or after November 15 and May 15 of each year and terminating on the last trading day on or before May 15 and November 15, approximately six months later, with identical purchase periods. Current employees cannot sell the shares of Class A common stock purchased under the ESPP until the day after the one-year anniversary of the purchase date of such shares, except for the withholding or sale of shares by the Company to meet any applicable tax withholding obligations. No employee may purchase (i) during each purchase period more than 1,500 shares of Class A common stock and (ii) shares under the ESPP at a rate in excess of $25,000 worth of the Company's Class A common stock based on the fair market value per share of the Company's Class A common stock at the beginning of an offering for each calendar year such purchase right is outstanding.
As of December 31, 2020, 639,773 shares of Class A common stock have been purchased under the ESPP. As of December 31, 2020 and 2019, the total unrecognized stock-based compensation expense related to the ESPP was
$2.0 million and $1.0 million, respectively, that is expected to be recognized over a weighted-average period of 0.4 years.
The weighted-average assumptions used to determine the fair value of the ESPP during the periods presented were as follows:
Year ended December 31,
20202019
Expected term (in years)0.50.7
Risk-free interest rate0.1 %1.8 %
Expected volatility63.1 %35.5 %
Dividend yield— — 
Stock-based Compensation Expense
The following table sets forth the total stock-based compensation expense included in the Company’s consolidated statements of operations:
Year Ended December 31,
202020192018
(in thousands)
Cost of revenue$1,225 $716 $119 
Sales and marketing16,019 8,709 979 
Research and development26,090 13,037 1,532 
General and administrative13,000 14,165 24,717 
Total stock-based compensation expense$56,334 $36,627 $27,347 
v3.20.4
Net Loss per Share Attributable to Common Stockholders
 12 Months Ended
Dec. 31, 2020
Earnings Per Share [Abstract]  
Net Loss per Share Attributable to Common Stockholders Net Loss per Share Attributable to Common Stockholders
The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders:

Year Ended December 31,

202020192018
Class AClass BClass AClass BCommon
(in thousands, except per share data)
Net loss attributable to common stockholders
$(70,955)$(48,415)$(18,259)$(87,569)$(87,164)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted
178,189 121,585 25,243 121,063 80,981 
Net loss per share attributable to common stockholders, basic and diluted
$(0.40)$(0.40)$(0.72)$(0.72)$(1.08)
Since the Company was in a loss position for all periods presented, basic net loss per share is the same as diluted net loss per share as the inclusion of all potential common shares outstanding would have been antidilutive. The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive are as follows:
December 31,
202020192018
(in thousands)
Convertible senior notes
15,363 — — 
Shares subject to repurchase
3,872 5,945 6,738 
Unexercised stock options
18,186 21,191 25,087 
Unvested restricted stock and RSUs
8,629 6,508 — 
Redeemable convertible preferred stock— — 165,658 
Redeemable convertible preferred stock warrants— — 177 
Vested and unreleased RSUs21 — — 
Shares issuable pursuant to the ESPP133 438 — 
Total
46,204 34,082 197,660 
v3.20.4
Income Taxes
 12 Months Ended
Dec. 31, 2020
Income Tax Disclosure [Abstract]  
Income Taxes Income Taxes
The components of the Company's loss before income taxes for the years ended December 31, 2020, 2019, and 2018 were as follows:
Year Ended December 31,
202020192018
(in thousands)
Domestic$(143,320)$(117,401)$(87,615)
Foreign18,347 12,688 1,528 
Total loss before income taxes$(124,973)$(104,713)$(86,087)
The components of the Company's provision for (benefit from) income taxes for the years ended December 31, 2020, 2019, and 2018 were as follows:
Year Ended December 31,
202020192018
(in thousands)
Current expense:
Federal$488 $391 $402 
State66 29 42 
Foreign769 325 248 
Total current provision for income taxes$1,323 $745 $692 
Deferred expense (benefit):
Federal(641)— (1)
State(140)— — 
Foreign(6,145)370 386 
Total deferred provision for (benefit from) income taxes$(6,926)$370 $385 
Total provision for (benefit from) income taxes$(5,603)$1,115 $1,077 
A reconciliation of the U.S. federal statutory rate to the Company's effective tax rate is as follows:
Year Ended December 31,
202020192018
Expected benefit at U.S. federal statutory rate21.0 %21.0 %21.0 %
State income taxes, net of federal tax benefits— — — 
Foreign income or losses taxed at different rates7.5 0.6 (1.3)
Stock-based compensation16.3 (1.2)(5.5)
Change in valuation allowance(39.4)(20.5)(14.0)
Withholding taxes(0.4)(0.4)(0.5)
Miscellaneous permanent items(0.5)(0.6)(1.0)
Total provision for (benefit from) income taxes4.5 %(1.1)%(1.3)%

In 2020, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets, offset by the partial release of the U.S. valuation allowance in connection with the acquisition of S2, excess tax benefits from stock-based compensation deductions in the United Kingdom, and income tax expense from profitable foreign jurisdictions. In 2019 and 2018, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was also primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets and income tax expense from profitable foreign jurisdictions.

The components of the Company's deferred tax assets and liabilities as of December 31, 2020 and 2019 were as follows:
Year Ended December 31,
20202019
(in thousands)
Deferred tax assets:
Net operating loss carryforwards$116,181 $53,536 
Tax credit carryforwards14,780 11,969 
Operating lease liabilities10,322 — 
Stock-based compensation10,118 6,852 
Accrued expenses and reserves2,615 1,988 
Depreciation and amortization4 85 
Other102 40 
Gross deferred tax assets154,122 74,470 
Valuation allowance(75,091)(63,487)
Total deferred tax assets$79,031 $10,983 
Deferred tax liabilities:
Convertible senior notes(43,889)— 
Right-of-use assets(10,626)— 
Deferred commissions(10,183)(5,487)
Capitalized internal-use software(7,405)(4,668)
Depreciation and amortization(1,326)(1,149)
Other(2)(225)
Total deferred tax liabilities$(73,431)$(11,529)
Net deferred tax assets (liabilities)$5,600 $(546)
In determining the need for a valuation allowance, the Company weighs both positive and negative evidence in the various jurisdictions in which it operates to determine whether it is more likely than not that its deferred tax assets are realizable. Accordingly, there is no valuation allowance in the foreign jurisdictions. A full valuation allowance has
been established in the U.S. and no deferred tax assets and related tax benefits have been recognized in the consolidated financial statements. The valuation allowance as of December 31, 2020 and 2019 was $75.1 million and $63.5 million, respectively. The net change in the valuation allowance for the years ended December 31, 2020, 2019, and 2018 was an increase of $11.6 million, an increase of $25.6 million and an increase of $15.5 million, respectively. The increase in the Company’s valuation allowance compared to the prior year was primarily due to an increase in U.S. deferred tax assets from increased U.S. taxable loss, offset by the partial release of the U.S. valuation allowance in connection with the acquisition of S2 and convertible note deferred tax liability.
As of December 31, 2020 and 2019, the Company had net operating loss carryforwards for federal income tax purposes of $448.7 million and $221.5 million, net of uncertain tax positions, respectively. The federal net operating loss carryforwards for tax years before December 31, 2017 will expire, if not utilized, beginning in the year 2029. Under the Tax Cuts and Jobs Act (The Tax Act), the federal net operating loss carryforwards for tax years after December 31, 2017 are carried forward indefinitely but are limited to 80% of taxable income; however, the Coronavirus Aid, Relief and Economic Security Act (The CARES Act) temporarily removes such limitations for years 2018 through 2020. Federal research and development tax credit carryforwards as of December 31, 2020 of $8.2 million, net of uncertain tax positions, will expire, if not utilized, beginning in the year 2029.
In addition, as of December 31, 2020 and 2019, the Company had net operating loss carryforwards for state income tax purposes of $215.8 million and $104.7 million, net of uncertain tax positions, respectively. The state net operating loss carryforwards will expire, if not utilized, beginning in the year 2026. The Company had state research and development tax credit carryforwards as of December 31, 2020 of $6.0 million, net of uncertain tax positions. The state research and development tax credits do not expire.

As of December 31, 2020 and 2019, the Company had foreign tax credit carryforwards for federal income tax purposes of $1.8 million. The federal foreign tax credit carryforwards will expire, if not utilized, beginning in the year 2025.
The Tax Reform Act of 1986 and similar California legislation impose substantial restrictions on the utilization of net operating losses and tax credit carryforwards in the event that there is a change in ownership as provided by Section 382 of the Internal Revenue Code and similar state provisions. Such a limitation could result in the expiration of the net operating loss carryforwards and tax credits before utilization.
A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows:
Year Ended December 31,
202020192018
(in thousands)
Balance as of the beginning of the period$3,740 $2,549 $2,247 
Increases for tax positions related to the prior year396 — — 
Decreases for tax positions related to the prior year(303)(120)(613)
Additions for tax positions related to the current year1,849 1,311 915 
Balance as of the end of the period$5,682 $3,740 $2,549 
The Company classifies uncertain tax positions as non-current income tax liabilities unless expected to be paid within one year or otherwise directly related to an existing deferred tax asset, in which case the uncertain tax position is recorded net of the asset on the consolidated balance sheet. As of December 31, 2020, $0.1 million of the Company’s gross unrecognized tax benefits, if recognized, would affect the effective tax rate and, $5.6 million would result in an adjustment to deferred tax assets with corresponding adjustments to valuation allowance. The Company does not expect any unrecognized tax benefits to be recognized within the next 12 months.
The Company’s policy is to recognize interest and penalties accrued on any unrecognized tax benefits as a component of income tax expense. The Company did not recognize any income tax expense related to interest and penalties in the years ended December 31, 2020, 2019, and 2018, respectively.
The Company’s significant tax jurisdictions include the U.S., Australia, Germany, Singapore, and the United Kingdom. Because of the net operating loss carryforwards, substantially all of the Company’s tax years remain open
to federal and state tax examination. The Company’s foreign tax returns are open to audit under the statutes of limitations of the respective foreign countries in which the subsidiaries are located.

The Company generally does not provide deferred income taxes for the undistributed earnings of its foreign subsidiaries as the Company intends to reinvest such earnings indefinitely. Should circumstances change and it becomes apparent that some or all of the undistributed earnings will no longer be indefinitely reinvested, the Company will accrue for income taxes not previously recognized. As of December 31, 2020, the majority of the Company's foreign subsidiaries had no cumulative undistributed earnings and, as a result, there were no unrecorded deferred tax liabilities. The amount of undistributed earnings in the Company’s other foreign subsidiaries are immaterial.
v3.20.4
Business Combinations
 12 Months Ended
Dec. 31, 2020
Business Combinations [Abstract]  
Business Combinations Business Combinations
In January 2020, the Company acquired all of the outstanding shares of S2, a company based in Kirkland, Washington that has developed browser isolation technology, for a total purchase consideration of $17.7 million. The Company is incorporating S2's technology into the Company's Cloudflare Gateway product. The total purchase consideration included (i) acquisition-date cash payments of $13.7 million, net of $0.1 million of cash acquired, (ii) $1.8 million in shares of the Company’s Class A common stock, and (iii) a cash holdback of $2.2 million, which the Company is retaining for up to 18 months and will be payable to the previous owners of S2, subject to offset by the Company for any of the previous owners’ indemnification obligations in connection with the acquisition. Concurrent with the closing of the acquisition, the Company made a cash payment of $6.9 million to repay S2’s debt, which was part of the acquisition-date cash payments included in the purchase consideration.
In connection with the acquisition, the Company entered into compensation arrangements for stock-based and cash awards with a value totaling $20.3 million, of which $5.7 million was recognized as compensation expense on the acquisition date and $5.7 million was recorded as additional compensation expense during the year ended December 31, 2020. The remaining compensation amount of $8.9 million is being recognized over a future weighted-average period of 2.2 years subject to the recipients’ continued service with the Company.
The transaction-related costs for the acquisition were not material and are included in general and administrative expenses in the consolidated statements of operations for the year ended December 31, 2020.
The fair values of assets acquired and liabilities assumed on the acquisition date are summarized as follows (in thousands):
Prepaid expenses and other current assets$6 
Developed technology5,600 
Goodwill13,084 
Total assets acquired18,690 
Accrued expenses and other current liabilities(208)
Other noncurrent liabilities(782)
Total purchase price$17,700 
A note payable of $0.2 million, included in accrued expenses and other current liabilities in the table above, assumed on the acquisition date, was paid off during the year ended December 31, 2020.
The acquired assets and assumed liabilities were recorded at their estimated fair values. The estimated useful life for the acquired developed technology is two years. The excess of the purchase price over the fair value of the net assets acquired was allocated to goodwill, none of which is expected to be deductible for tax purposes. Goodwill is primarily attributable to the assembled workforce as well as the anticipated synergies from the integration of S2's technology with the Company's technology. A purchase accounting adjustment of $0.8 million to revise purchase consideration and goodwill was made during the year ended December 31, 2020.
This acquisition did not have a material impact on the Company’s consolidated financial statements; therefore, historical and pro forma disclosures have not been presented.
v3.20.4
Segment and Geographic Information
 12 Months Ended
Dec. 31, 2020
Segment Reporting [Abstract]  
Segment and Geographic Information Segment and Geographic Information
The Company’s chief operating decision maker (CODM) is its CEO, COO, and CFO. Collectively, the CODM reviews financial information presented on a consolidated basis for purposes of allocating resources and evaluating financial performance. The Company has no segment managers who are held accountable by the CODM for operations, operating results, and planning for levels or components below the consolidated unit level. Accordingly, the Company has determined it has a single operating segment.
Refer to Note 3 to these consolidated financial statements for revenue by geography.
The Company’s property and equipment, net, by geographic area were as follows:
December 31,
20202019
(in thousands)
United States$79,078 $59,688 
Rest of the world44,610 41,778 
Total property and equipment, net$123,688 $101,466 
No single country other than the United States accounted for more than 10% of total property and equipment, net as of December 31, 2020 and 2019.
v3.20.4
Summary of Significant Accounting Policies (Policies)
 12 Months Ended
Dec. 31, 2020
Accounting Policies [Abstract]  
Basis of Presentation The accompanying consolidated financial statements and accompanying notes have been prepared in conformity with generally accepted accounting principles in the United States (U.S. GAAP) and include the accounts of the Company and its wholly-owned subsidiaries.
Principles of Consolidation All intercompany balances and transactions have been eliminated in consolidation.
Fiscal Period The Company’s fiscal year ends on December 31.
Initial Public Offering
In September 2019, the Company completed an initial public offering (IPO) in which it issued and sold Class A common stock for net proceeds of $565.0 million, after deducting underwriting discounts and commissions and offering costs. Upon completion of the IPO, all of the Company's outstanding redeemable convertible preferred stock was automatically converted into Class A common stock and Class B common stock. In addition, all of the outstanding warrants to purchase shares of the Company's redeemable convertible preferred stock were automatically converted into outstanding warrants to purchase shares of Class B common stock, and all of the shares of Class B common stock held by former employees was automatically converted into Class A common stock.
Use of Estimates The preparation of consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the amounts reported and disclosed in the consolidated financial statements and accompanying notes to the consolidated financial statements. Such estimates include, but are not limited to, allowance for doubtful accounts, deferred contract acquisitions costs, the period of benefit generated from the Company’s deferred contract acquisition costs, the capitalization and estimated useful life of internal-use software, the assessment of recoverability of intangible assets and their estimated useful lives, useful lives of property and equipment, liability and equity allocation of convertible senior notes, the determination of the incremental borrowing rate used for operating lease liabilities, the valuation and recognition of stock-based compensation expense, uncertain tax positions, and the recognition and measurement of current and deferred income tax assets and liabilities. Management bases these estimates and assumptions on historical experience and on various other assumptions that are believed to be reasonable. Due to the COVID-19 pandemic, there is ongoing uncertainty and significant disruption in the global economy and financial markets. The Company is not aware of any specific event or circumstance that would require an update to its estimates or assumptions or a revision of the carrying value of its assets or liabilities as of February 25, 2021, the date of issuance of this Annual Report on Form 10-K. These estimates and assumptions may change in the future, however, as new events occur and additional information is obtained. Actual results could differ materially from these estimates.
Concentration of Risks The Company’s revenue is reliant on its customers utilizing Internet-based services. These services can be prone to rapid changes in technology and government regulation. If the Company were unable to keep pace with customers’ needs and continue to improve its technological capabilities, or if another firm were to introduce competitive
products, or a government jurisdiction were to enact legislation detrimental to the Company’s business, such an event or events could adversely affect the Company’s operating results.
The Company serves its customers from co-location facilities located in various cities and countries around the world. The Company has internal procedures to restore services in the event of disasters at its current co-location facilities. Even with these procedures for disaster recovery in place, the Company’s services could be significantly interrupted during the implementation of restoration procedures.
The Company’s financial instruments that are exposed to concentrations of credit risk consist primarily of cash, cash equivalents, available-for-sale securities, and accounts receivable. Although the Company maintains cash deposits, cash equivalent balances, and available-for-sale securities with multiple financial institutions, the deposits, at times, may exceed federally insured limits. Cash and cash equivalents may be withdrawn or redeemed on demand. The Company believes that the financial institutions that hold its cash and cash equivalents are financially sound and, accordingly, minimal credit risk exists with respect to these balances. The Company also maintains investments in U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds that carry high credit ratings and accordingly, minimal credit risk exists with respect to these balances. Cash equivalents consist of money market funds, commercial paper, and corporate bonds which are invested through financial institutions in the United States.
The Company’s accounts receivable are derived from net revenue to customers located throughout the world. The Company grants credit to its customers in the normal course of business.
Revenue Recognition
In accordance with ASC 606, revenue is recognized when a customer obtains control of promised services. The amount of revenue recognized reflects the consideration that the Company expects to be entitled to receive in exchange for these services. To achieve this standard, the Company applies the following five steps:
1. Identify the contract with a customer
2. Identify the performance obligations in the contract
3. Determine the transaction price
4. Allocate the transaction price to performance obligations in the contract
5. Recognize revenue when or as the Company satisfies a performance obligation
The Company generates sales directly through its sales team and through its channel partners. Revenue from sales to channel partners are recorded once all revenue recognition criteria above are met. Channel partners generally receive an order from an end-customer prior to placing an order with the Company. Payment from channel partners is not contingent on the partner’s collection from end-customers. The Company’s performance obligation primarily consists of subscription and support services, as they are provided over the same service period.
Variable Consideration
If the Company’s services do not meet certain service level commitments, its customers are entitled to receive service credits, and in certain cases, refunds, each representing a form of variable consideration. Revenue from sales is recorded at the net sales price, which is the transaction price, and includes estimates of these forms of variable consideration to the extent that a significant reversal of cumulative revenue will not occur in a future period. The Company has historically not experienced any incidents that had a material impact on its consolidated financial statements. Accordingly, any estimated refunds related to these agreements in the consolidated financial statements are not material during the periods presented. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s network and products in a given period and is recognized as revenue in the period in which the usage occurs.
Subscription and Support Revenue
The Company generates revenue primarily from sales to its customers of subscriptions to access its network and products, together with related support services. Arrangements with customers generally do not provide the customer with the right to take possession of the Company’s software operating its global network and products at any time. Instead, customers are granted continuous access to the Company’s global network and products over the contractual period. Access to the Company’s network and products is considered a monthly series comprising one performance obligation. A time-elapsed output method is used to measure progress because the Company transfers control evenly over the contractual period. Accordingly, the fixed consideration related to subscription and support revenue is generally recognized on a straight-line basis over the contract term beginning on the date that the Company’s service is made available to the customer. Usage-based consideration is primarily related to fees charged for the Company’s customer’s use of excess bandwidth when accessing the Company’s network and products in a given period and is recognized as revenue in the period in which the usage occurs.
The subscription and support term contracts for the Company’s contracted customers, typically range from one to three years. Most of the Company’s contracts with contracted customers are non-cancelable over the contractual term. Customers typically have the right to terminate their contracts for cause, if the Company fails to perform in accordance with the contractual terms. For the Company’s pay-as-you-go customers, which consist of customers that sign up for the Company's Pro or Business subscription plans through the Company's website (and which the Company previously referred to as self-serve customers), subscription and support terms are typically monthly.
Costs to Obtain and Fulfill a Contract
The Company capitalizes sales commission and associated payroll taxes paid to internal sales personnel that are incremental to the acquisition of channel partner and direct customer contracts. These costs are recorded as deferred contract acquisition costs on the consolidated balance sheets. The Company determines whether costs should be deferred based on its sales compensation plans, if the commissions are in fact incremental and would not have occurred absent the customer contract.
Sales commissions for renewal of a contract are not considered commensurate with the commissions paid for the acquisition of the initial contract. Commissions paid upon the initial acquisition of a contract are amortized over an estimated period of benefit of three years while commissions paid for renewal contracts are amortized over the contractual term of the renewals. Amortization of deferred contract acquisition costs is recognized on a straight-line basis commensurate with the pattern of revenue recognition and included in sales and marketing expense in the consolidated statements of operations. The Company determines the period of benefit for commissions paid for the acquisition of the initial contract by taking into consideration the expected subscription term and expected renewals of its customer contracts, the duration of its relationships with its customers, customer retention data, its technology development lifecycle, and other factors. The Company periodically reviews the carrying amount of deferred contract acquisition costs to determine whether events or changes in circumstances have occurred that could impact the period of benefit of these deferred costs.
Disaggregation of Revenue
Subscription and support revenue is recognized over time and accounted for substantially all of the Company’s revenue for the years ended December 31, 2020, 2019, and 2018.
Contract Balances
Contract liabilities consist of deferred revenue and include payments received in advance of performance under the contract. Such amounts are recognized as revenue over the contractual period. For the years ended December 31, 2020, 2019, and 2018 the Company recognized revenue of $31.3 million, $16.8 million, and $11.9 million, respectively, that was included in the corresponding contract liability balance at the beginning of the periods presented.
The Company receives payments from customers based upon contractual billing schedules; accounts receivable are recorded when the right to consideration becomes unconditional. Standard payment terms are due upon receipt. Contract assets include amounts related to the Company’s contractual right to consideration for both completed and partially completed performance obligations that have not been invoiced.
Accounts Receivable and Allowance Accounts receivable are recorded at the invoiced amount and are non-interest bearing. Accounts receivable are stated at their net realizable value, net of a sales allowance and an allowance for doubtful accounts. Credit is extended to customers based on an evaluation of their financial condition and other factors. The Company establishes a sales allowance at the time of revenue recognition based on its history of adjustments and credits provided to customers. In determining the necessary allowance for doubtful accounts, the Company considers the current aging and financial condition of its customers, the amount of receivables in dispute, and current payment patterns. Accounts receivable are written off against the allowance when management determines a balance is uncollectible and the Company no longer actively pursues collection of the receivable. The Company does not have any off-balance-sheet credit exposure related to its customers.
Cost of Revenue Cost of revenue consists primarily of expenses that are directly related to providing the Company's service to its paying customers. These expenses include expenses related to operating in co-location facilities, network and bandwidth costs, depreciation of the Company's equipment located in co-location facilities, certificate authority services costs for paying customers, related overhead costs, the amortization of the Company's capitalized internal-use software, and the amortization of acquired developed technologies. Cost of revenue also includes employee-related costs, including salaries, bonuses, benefits, and stock-based compensation for employees whose primary responsibilities relate to supporting the Company's paying customers and delivering paid customer support. Other costs included in cost of revenue include credit card fees related to processing customer transactions and allocated overhead costs.
Research and Development The Company charges costs related to research, design, and development of products to research and development expense in the consolidated statements of operations as incurred. Research and development expenses support the Company's efforts to add new features to its existing offerings and to ensure the security, performance, and reliability of its global network. The majority of the Company's research and development expenses result from employee-related costs, including salaries, bonuses and benefits, consulting costs, depreciation of equipment used in research and development, and allocated overhead costs.
Advertising Expense Advertising costs are charged to sales and marketing expense in the consolidated statements of operations as incurred.
Stock-based Compensation
The Company measures and recognizes stock-based compensation expense based on the grant date fair value of the awards. The grant date fair value of stock options is estimated using the Black-Scholes option pricing model. The grant date fair value of restricted stock units (RSUs) is estimated based on the fair value of the Company's underlying common stock. The grant date fair value and the stock-based compensation expense related to purchase rights issued under the 2019 Employee Stock Purchase Plan (ESPP) is estimated using the Black-Scholes option pricing model and is based on the estimated number of awards as of the beginning of the offering period, respectively.
The Black-Scholes option pricing model requires the use of highly subjective assumptions, including the award’s expected term, the fair value of the underlying common stock, the expected volatility of the price of the common stock, risk-free interest rates, and the expected dividend yield of the common stock. The assumptions used to determine the fair value of the stock-based awards are management’s best estimates and involve inherent uncertainties and the application of judgment. The expected term represents the period that the Company’s stock-based awards are expected to be outstanding. As the Company does not have sufficient historical experience for determining the expected term of the stock option awards granted, it has based its expected term on the simplified method available under U.S. GAAP. Stock-based compensation expense for awards with service-based vesting only is recognized on a straight-line basis over the requisite service period of the awards, which is generally four years. The Company accounts for forfeitures as they occur.
Prior to the IPO, the fair value of the Company's common stock for financial reporting purposes was determined considering numerous objective and subjective factors and required judgment to determine the fair value of common stock as of each grant date. Subsequent to the IPO, the Company determines the fair value using the market closing price of its Class A common stock on the date of grant.
Income Taxes The Company accounts for income taxes using the asset and liability method. Deferred income taxes are recognized by applying the enacted statutory tax rates applicable to future years to differences between the carrying amounts of existing assets and liabilities and their respective tax bases and net operating loss and tax credit carryforwards. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. The measurement of deferred tax assets is reduced, if necessary, by a valuation allowance to amounts that are more likely than not to be realized.The Company recognizes tax benefits from uncertain tax positions only if it believes that it is more likely than not that the tax position will be sustained on examination by the taxing authorities based on the technical merits of the position.
Foreign Currency Remeasurement The Company's functional currency of its foreign subsidiaries is the U.S. dollar. The monetary assets and liabilities that are denominated in a currency other than the U.S. dollar of the Company's foreign subsidiaries are remeasured into U.S. dollars at the exchange rate on the balance sheet date, while nonmonetary items are remeasured at historical rates. Revenue and expenses are remeasured at average exchange rates during the period. Transaction gains and losses that arise from exchange rate fluctuations on transactions denominated in a currency other than the functional currency are included in other income (expense), net in the consolidated statements of operations.
Cash and Cash Equivalents Cash and cash equivalents consist of highly liquid investments with an original maturity from the date of purchase of 90 days or less.
Available-for-sale securities and Other-than-temporary impairment The Company’s available-for-sale securities consist of U.S. treasury securities, U.S. government agency securities, commercial paper, and corporate bonds. The Company has designated all securities held by it as available-for-sale and therefore, such securities are reported at fair value, with unrealized gains and losses recorded in accumulated other comprehensive loss on the consolidated balance sheets. For securities sold prior to maturity, the cost of securities sold is based on the specific identification method. Realized gains and losses on the sale of available-for-sale securities are recorded in other income (expense), net in the consolidated statements of operations. All securities are classified within current assets as such securities can be liquidated to fund current operations without penalty. All of the Company’s investments are subject to a periodic impairment review. The Company recognizes an impairment charge when a decline in the fair value of its investments below the cost basis is determined to be other-than-temporary. Factors considered in determining whether a loss is temporary include the extent and length of time the investment’s fair value has been lower than its cost basis, the financial condition and near-term prospects of the investee, the extent of the loss related to credit of the issuer, the expected cash flows from the security, the Company’s intent to sell the security, and whether or not the Company will be required to sell the security prior to the expected recovery of the investment’s amortized cost basis.
Fair Value Measurements The carrying value of the Company’s financial instruments, including cash equivalents, available-for-sale securities, accounts receivable, accounts payable, and accrued expenses, approximates fair value due to their short-term nature.
Property and Equipment
Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows:
Useful Lives
Servers—network infrastructure4 years
Buildings30 years
Office and computer equipment3 years
Office furniture3 years
Software3 years
Leasehold improvementsLesser of useful life or term of lease
Asset retirement obligationLesser of useful life or term of lease
Expenditures for maintenance and repairs are expensed as incurred.
Capitalized Internal-Use Software Development Costs Certain development costs related to the Company’s global network and products during the application development stage are capitalized. Costs incurred in the preliminary stages of development are analogous to research and development activities and are expensed as incurred. The preliminary stage includes such activities as conceptual formulation of alternatives, evaluation of alternatives, determination of existence of needed technology, and final selection of alternatives. Once the application development stage is reached, internal and external costs are capitalized until the software is substantially complete and ready for its intended use. Capitalized costs are recorded as part of property and equipment, net. Capitalized internal-use software is amortized on a straight-line basis over its estimated useful life, which is generally three years, and is recorded as cost of revenue in the consolidated statements of operations.
Business Combinations
The Company includes the results of operations of the businesses that the Company acquires from the date of acquisition. The fair value of the assets acquired and liabilities assumed is based on their estimated fair values as of the respective date of acquisition. The excess purchase price over the fair value of the net assets acquired and liabilities assumed is recorded as goodwill. Determining the fair value of assets acquired and liabilities assumed requires significant judgment and estimates including the selection of valuation methodologies, future expected cash flows, discount rates, and useful lives. The Company’s estimates of fair value are based on assumptions believed to be reasonable, but which are inherently uncertain and, as a result, actual results may differ from estimates. During the measurement period, not to exceed one year from the date of acquisition, the Company may record adjustments to the assets acquired and liabilities assumed with a corresponding offset to goodwill. At the conclusion of the measurement period, or final determination of the values of assets acquired or liabilities assumed, whichever comes first, any subsequent adjustments are reflected in the consolidated statements of operations.
When the Company issues payments or grants of equity to selling stockholders in connection with an acquisition, the Company evaluates whether the payments or awards are compensatory. This evaluation includes whether cash payments or stock award vesting is contingent on the continued employment of the selling stockholder beyond the acquisition date. If continued employment is required for the cash to be paid or stock awards to vest, the award is treated as compensation for post-acquisition services and is recognized as compensation expense.
Transaction costs associated with business combinations are expensed as incurred, and are included in general and administrative expense in the Company’s consolidated statements of operations.
Convertible Senior Notes The Company accounts for its 0.75% Convertible Senior Notes due May 2025 (the Notes) as separate liability and equity components. The carrying amount of the liability component was calculated by measuring the fair value of a similar debt instrument that does not have an associated convertible feature. The carrying amount of the equity component, representing the conversion option, was calculated by deducting the fair value of the liability component from the total principal of the convertible notes. The excess of the principal amount of the liability component over its book value (debt discount) is amortized to interest expense over the term of the Notes. In accounting for the issuance costs related to the Notes, the allocation of issuance costs incurred between the liability and equity components was based on their relative values. Issuance costs attributable to the liability component are being amortized over the contractual term of the Notes.
Goodwill and Intangible Assets Goodwill represents the excess of the purchase price of an acquired business over the fair value of the net tangible and identifiable intangible assets acquired. The carrying amount of goodwill is reviewed for impairment at least annually, in the fourth quarter, or whenever events or changes in circumstances indicate that the carrying value may not be recoverable. At December 31, 2020 and 2019, the Company had a single operating segment and reporting unit structure. As part of the annual goodwill impairment test, the Company first performs a qualitative assessment to determine whether further impairment testing is necessary. If, as a result of the qualitative assessment, it is more likely than not that the fair value of the reporting unit is less than its carrying amount, the quantitative impairment test will be required. If the Company has determined it necessary to perform a quantitative impairment assessment,
the Company will compare the fair value of the reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value, limited to the total amount of goodwill of the reporting unit. The Company did not recognize any goodwill impairment charges for any of the periods presented.
Intangible assets are carried at cost, net of accumulated amortization. Intangible assets are amortized on a straight-line basis over their estimated useful lives. The Company estimates the useful life by estimating the expected period of economic benefit. The estimated useful life of the Company’s acquired developed technology intangible assets is two years.
Indefinite lived intangibles are assessed annually for impairment, which includes an assessment of whether there were any triggering events that required an impairment assessment of the Company’s definite lived intangible assets, and whether it was more likely than not that the Company’s indefinite lived intangible asset was impaired. The Company’s indefinite lived intangible assets arose from an asset acquisition in November 2017.
Impairment of Long-Lived Assets The Company evaluates long-lived assets, which include depreciable tangible assets, for impairment whenever events or changes in circumstances indicate that the carrying value of long-lived assets may not be recoverable. The recoverability of these assets is measured by comparing the carrying amounts to the future undiscounted cash flows these assets are expected to generate. The Company recognizes an impairment in the event the carrying amount of such assets exceeds the fair value attributable to such assets. There were no events or changes in circumstances that indicated the long-lived assets were impaired during any of the periods presented.
Operating Leases The Company enters into lease arrangements for real estate assets related to office space and for co-location assets related to space and equipment located in co-location facilities. The Company determines if an arrangement is, or contains, a lease at its inception by assessing whether there is an identified asset and whether the arrangement conveys the right to control the use of the identified asset in exchange for consideration for a period of time. All of the Company's leases are classified as operating leases. At lease commencement, the Company recognizes right-of-use assets, operating lease liabilities, and operating lease liabilities, noncurrent in the Company’s consolidated balance sheets, with the exception of short-term leases with an original term of 12 months or less. Right-of-use assets represent the Company's right to use an underlying asset for the lease term including any renewal options that it is reasonably certain to renew. The Company generally uses the base, non-cancelable lease term when recognizing the right-of-use assets and lease liabilities, unless it is reasonably certain that a renewal or termination option will be exercised. Operating lease liabilities represent the present value of the Company's obligation to make payments arising from the lease. Right-of-use assets are initially measured based on the corresponding lease liability adjusted for (i) payments made to the lessor at or before the commencement date, (ii) initial direct costs incurred and (iii) tenant incentives received, incurred or payable under the lease. Right-of-use assets are periodically reviewed for impairment. Lease liabilities are initially measured at the present value of total minimum lease payments not yet paid. As the implicit rate of the Company's leases is not determinable, the Company uses an incremental borrowing rate (IBR) based on the information available at the lease commencement date in determining the present value of lease payments. Minimum lease payments consist of the fixed payments under the arrangement and variable payments that depend on an underlying index or rate, less any lease incentives such as tenant improvement allowances not yet received at commencement date. Variable lease costs that do not depend on an index or a rate are expensed as incurred and not included within the calculation of right-of-use assets and lease liabilities. The Company's operating lease arrangements contain both lease and non-lease components. At inception of an arrangement, the Company allocates the consideration to the lease and non-lease components and recognizes a right-of-use asset and corresponding lease liability for only the lease components. Lease expense for operating leases is recognized on a straight-line basis over the term of the lease.
Legal Contingencies The Company accrues a liability for an estimated loss for legal contingencies if the potential loss from any claim or legal proceeding is considered probable, and the amount can be reasonably estimated. The Company believes there are no legal proceedings pending that could have, individually or in the aggregate, a material adverse effect on its results of operations or financial condition.
Net Loss per Share Attributable to Common Stockholders
Basic and diluted net loss per share attributable to common stockholders is presented in conformity with the two-class method required for multiple classes of common stock and participating securities. The Company considers its previously outstanding redeemable convertible preferred stock to be participating securities. The Company also considers any shares issued on the early exercise of stock options subject to repurchase to be participating securities because holders of such shares have nonforfeitable dividend rights in the event a dividend is paid on common stock. Under the two-class method, net income is attributed to common stockholders and participating securities based on their participation rights. The holders of the redeemable convertible preferred stock, as well as the holders of early exercised shares subject to repurchase, do not have a contractual obligation to share in the losses of the Company. As such, the Company’s net losses for the years ended December 31, 2020, 2019, and 2018 were not allocated to these participating securities. The rights, including the liquidation and dividend rights, of the Class A common stock and Class B common stock are substantially identical, other than voting rights. Accordingly, the Class A common stock and Class B common stock share proportionately in the Company’s net losses. Prior to the completion of the IPO, there were no shares of Class A common stock issued and outstanding.
Under the two-class method, basic net loss per share attributable to common stockholders is computed by dividing the net loss attributable to common stockholders by the weighted-average number of shares of common stock outstanding during the period, less shares subject to repurchase. Vested RSUs that have not been settled have been included in the appropriate common share class used to calculate basic net loss per share.
Diluted net loss per share attributable to common stockholders adjusts basic net loss per share for the effect of dilutive securities, including awards under the Company's equity incentive plans. As the Company has reported losses for all periods presented, all potentially dilutive securities are antidilutive and accordingly, basic net loss per share equals diluted net loss per share.
Segment and Geographic Information The Company has one reportable and operating segment.
Recent Accounting Pronouncements
In February 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update (ASU) No. 2016-02, Leases (Topic 842), and since that date, has issued several ASUs to further clarify certain aspects of ASU 2016-02 and provide entities with practical expedients that may be elected upon adoption. The Company adopted the new standard beginning January 1, 2020 using the modified retrospective approach, electing the optional transition approach of not adjusting the comparative period financial statements for the impact of adoption. The Company elected the package of practical expedients permitted under the transition guidance, which allows the Company to carryforward its historical lease classification, its assessment on whether a contract is or contains a lease, and its initial direct costs for any leases that existed prior to adoption of the new standard. In addition, the Company elected not to recognize lease liabilities and related right-of-use assets for leases that, at the lease commencement date, have a lease term of 12 months or less. Adoption of the new standard on January 1, 2020 resulted in the recognition of $50.0 million of operating lease right-of-use assets and $52.8 million of total operating lease liabilities on the Company's consolidated balance sheets. As part of the adoption, the Company also derecognized deferred rent of $2.8 million, primarily consisting of the noncurrent portion, net build-to-suit assets of $9.9 million, the build-to-suit lease financing obligation of $10.5 million, and recorded a cumulative-effect adjustment of $0.6 million to accumulated deficit as of January 1, 2020. Refer to Note 6 to these consolidated financial statements.
In June 2016, the FASB issued ASU 2016-13, Financial Instruments-Credit Losses (Topic 326), Measurement of Credit Losses on Financial Instruments. This ASU changes the methodology for measuring credit losses and
requires the establishment of an allowance for estimated credit losses on financial assets, including trade and other receivables, at each reporting date. The Company adopted ASU 2016-13 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In August 2018, the FASB issued ASU 2018-15, Intangibles—Goodwill and Other—Internal-Use Software (ASC 350-40): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement. This guidance provides that implementation costs be evaluated for capitalization using the same criteria as that used for internal-use software development costs, with amortization expense being recorded in the same income statement expense line as the hosted service costs and over the expected term of the hosting arrangement. For public business entities, it is effective for fiscal years beginning after December 15, 2019, and interim periods within those fiscal years. Early adoption of the amendments in this update is permitted, including adoption in any interim period, for all entities. The Company adopted ASU 2018-15 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In November 2019, the FASB issued ASU 2019-10, Financial Instruments—Credit Losses (Topic 326), Derivatives and Hedging (Topic 815), and Leases (Topic 842). This ASU revises, and staggers, the effective dates for various major updates that have been issued since 2014 to alleviate the burden on both larger public companies as well as private companies, smaller public companies, not-for-profit organizations, and employee benefit plans. The Company adopted ASU 2019-10 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
In December 2019, the FASB issued ASU 2019-12, Simplifying the Accounting for Income Taxes (ASC Topic 740). This ASU simplifies accounting for income taxes by removing certain exceptions to the general principles and amending existing guidance to improve consistent application. The amendments in this update are effective for fiscal years, and interim periods within those fiscal years, beginning after December 15, 2020, with early adoption permitted. The Company adopted ASU 2019-12 effective January 1, 2020, noting no material impact on the Company’s consolidated financial statements.
Recently Issued Accounting Pronouncements
In August 2020, the FASB issued ASU 2020-06, Debt—Debt with Conversion and Other Options (ASC 470-20) and Derivatives and Hedging - Contracts in Entity's Own Equity (ASC 815-40). The FASB issued this ASU to simplify the accounting for certain financial instruments with characteristics of liabilities and equity, including convertible instruments and contracts on an entity's own equity. The Company does not have any contracts on its own equity; however, the Company does have convertible debt. This ASU removes the separation models for 1) convertible debt with a cash conversion feature and 2) convertible instruments with a beneficial conversion feature, as well as enhances the related disclosure and earnings per share guidance. Additionally, this update requires that convertible debt be recognized as a single liability measured at its amortized cost, if no bifurcation is required, and as a result, interest expense will be closer to the coupon interest rate. For public business entities, these amendments are effective for fiscal years beginning after December 15, 2021, with early adoption permitted for fiscal years beginning after December 15, 2020. The Company is currently evaluating the impact of this accounting standard update on its consolidated financial statements.
v3.20.4
Summary of Significant Accounting Policies (Tables)
 12 Months Ended
Dec. 31, 2020
Accounting Policies [Abstract]  
Schedule of Property and Equipment
Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows:
Useful Lives
Servers—network infrastructure4 years
Buildings30 years
Office and computer equipment3 years
Office furniture3 years
Software3 years
Leasehold improvementsLesser of useful life or term of lease
Asset retirement obligationLesser of useful life or term of lease
Property and equipment, net consisted of the following:
December 31,
20202019
(in thousands)
Property and equipment:
Servers—network infrastructure$108,988 $84,979 
Buildings— 13,035 
Construction in progress11,242 8,692 
Capitalized internal-use software49,618 31,171 
Office and computer equipment17,867 13,528 
Office furniture5,657 6,124 
Software1,808 1,025 
Leasehold improvements10,686 9,870 
Asset retirement obligation430 231 
Gross property and equipment206,296 168,655 
Less accumulated depreciation and amortization(82,608)(67,189)
Total property and equipment, net$123,688 $101,466 
v3.20.4
Revenue (Tables)
 12 Months Ended
Dec. 31, 2020
Revenue from Contract with Customer [Abstract]  
Schedule of Disaggregation of Revenue The following table summarizes the revenue by region based on the billing address of customers who have contracted to use the Company’s global network and products:
Year Ended December 31,
202020192018
(in thousands)
AmountPercentage
of Revenue		AmountPercentage
of Revenue		AmountPercentage
of Revenue
United States$218,191 51 %$144,575 50 %$92,652 48 %
Europe, Middle East, and Africa
109,274 25 %68,418 24 %48,438 25 %
Asia Pacific76,177 18 %55,131 19 %38,851 20 %
Other27,417 6 %18,898 7 %12,733 7 %
Total$431,059 100 %$287,022 100 %$192,674 100 %
The following table summarizes the revenue from contracts by type of customer:
Year Ended December 31,
202020192018
(in thousands)
AmountPercentage
of Revenue		AmountPercentage
of Revenue		AmountPercentage
of Revenue
Channel partners
$45,300 11 %$26,496 9 %$13,231 7 %
Direct customers
385,759 89 %260,526 91 %179,443 93 %
Total$431,059 100 %$287,022 100 %$192,674 100 %
Summary of Deferred Contract Acquisition Costs
The following table summarizes the activity of the deferred contract acquisition costs:
Year Ended December 31,
202020192018
(in thousands)
Beginning balance$25,184 $15,940 $10,765 
Capitalization of contract acquisition costs
36,316 20,065 12,235 
Amortization of deferred contract acquisition costs
(17,324)(10,821)(7,060)
Ending balance$44,176 $25,184 $15,940 
v3.20.4
Fair Value Measurements (Tables)
 12 Months Ended
Dec. 31, 2020
Fair Value Disclosures [Abstract]  
Schedule of Fair Value by Significant Investment Category The following table summarizes the Company’s cash and available-for-sale securities’ amortized cost, unrealized gains (losses), and fair value by significant investment category reported as cash and cash equivalents, restricted cash, or available-for-sale securities as of December 31, 2020 and 2019.
(in thousands)    Reported as:
December 31, 2020Amortized
Cost		Unrealized
Gain		Unrealized
(Loss)		Fair ValueCash & Cash EquivalentsAvailable-for-sale SecuritiesRestricted Cash
Cash$22,114 $— $— $22,114 $19,523 $— $2,591 
Level I:
Money market funds
71,038 — — 71,038 64,378 — 6,660 
Level II:
Corporate bonds
169,324 43 (26)169,341 — 169,341 — 
U.S. treasury securities
576,652 223 (4)576,871 — 576,871 — 
U.S. government agency securities
15,617 4 (1)15,620 — 15,620 — 
Commercial paper
186,363 — — 186,363 24,994 161,369 — 
Subtotal
947,956 270 (31)948,195 24,994 923,201 — 
Total assets measured at fair value on a recurring basis
$1,041,108 $270 $(31)$1,041,347 $108,895 $923,201 $9,251 

(in thousands)Reported as:
December 31, 2019Amortized
Cost		Unrealized
Gain		Unrealized
(Loss)		Fair ValueCash & Cash EquivalentsAvailable-for-sale SecuritiesLong-term Restricted Cash
Cash$24,631 $— $— $24,631 $24,631 $— $— 
Level I:
Money market funds
32,856 — — 32,856 26,196 — 6,660 
Level II:
Corporate bonds
84,054 22 (30)84,046 — 84,046 — 
U.S. treasury securities
311,083 151 (23)311,211 — 311,211 — 
U.S. government agency securities
95,380 17 — 95,397 22,549 72,848 — 
Commercial paper
95,467 — — 95,467 65,600 29,867 — 
Subtotal
585,984 190 (53)586,121 88,149 497,972 — 
Total assets measured at fair value on a recurring basis
$643,471 $190 $(53)$643,608 $138,976 $497,972 $6,660 
v3.20.4
Balance Sheet Components (Tables)
 12 Months Ended
Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]  
Schedule of Activity in Allowance for Doubtful Accounts
Activity in the allowance for doubtful accounts was as follows:
December 31,
202020192018
(in thousands)
Beginning balance$533 $160 $— 
Provision for bad debt3,368 2,488 1,080 
Write-off of uncollectible accounts receivable(2,198)(2,115)(920)
Ending balance$1,703 $533 $160 
Schedule of Prepaid Expenses and Other Current Assets
Prepaid expenses and other current assets consisted of the following:
 December 31,
20202019
 (in thousands)
Prepaid expenses$13,689 $10,913 
Deposits4,246 2,773 
Other10,295 3,308 
Total prepaid expenses and other current assets$28,230 $16,994 
Schedule of Property and Equipment, Net
Property and equipment are stated at cost, net of accumulated depreciation. Depreciation is computed on a straight-line basis over the estimated useful lives of the assets, which is generally as follows:
Useful Lives
Servers—network infrastructure4 years
Buildings30 years
Office and computer equipment3 years
Office furniture3 years
Software3 years
Leasehold improvementsLesser of useful life or term of lease
Asset retirement obligationLesser of useful life or term of lease
Property and equipment, net consisted of the following:
December 31,
20202019
(in thousands)
Property and equipment:
Servers—network infrastructure$108,988 $84,979 
Buildings— 13,035 
Construction in progress11,242 8,692 
Capitalized internal-use software49,618 31,171 
Office and computer equipment17,867 13,528 
Office furniture5,657 6,124 
Software1,808 1,025 
Leasehold improvements10,686 9,870 
Asset retirement obligation430 231 
Gross property and equipment206,296 168,655 
Less accumulated depreciation and amortization(82,608)(67,189)
Total property and equipment, net$123,688 $101,466 
Schedule of Acquired Intangible Assets, Net
Acquired intangible assets, net consisted of the following:
December 31, 2020
Gross Carrying
Amount		Accumulated
Amortization		Net Book
Value
(in thousands)
Developed technology$5,600 $2,800 $2,800 
Total acquired intangible assets, net$5,600 $2,800 $2,800 

December 31, 2019
Gross Carrying
Amount		Accumulated
Amortization		Net Book
Value
(in thousands)
Developed technology$250 $219 $31 
Total acquired intangible assets, net$250 $219 $31 
Schedule of Estimated Future Amortization Expense of Acquired Intangible Assets
As of December 31, 2020, the estimated future amortization expense of acquired intangible assets was as follows:
Estimated
Amortization
(in thousands)
Year ending December 31,
2021$2,800 
Total$2,800 
Schedule of Accrued Expenses
Accrued expenses and other current liabilities consisted of the following:
December 31,
20202019
(in thousands)
Accrued compensation and benefits$25,410 $14,970 
Accrued expenses6,916 5,331 
Customer refunds and credits1,548 3,328 
Accrued co-location and bandwidth5,205 2,696 
Other6,548 1,989 
Total accrued expenses and other current liabilities$45,627 $28,314 
Schedule of Other Current Liabilities
Accrued expenses and other current liabilities consisted of the following:
December 31,
20202019
(in thousands)
Accrued compensation and benefits$25,410 $14,970 
Accrued expenses6,916 5,331 
Customer refunds and credits1,548 3,328 
Accrued co-location and bandwidth5,205 2,696 
Other6,548 1,989 
Total accrued expenses and other current liabilities$45,627 $28,314 
Schedule of Other Noncurrent Liabilities Other noncurrent liabilities consisted of the following:
December 31,
20202019
(in thousands)
Accrued taxes$7,033 $4,862 
Deferred rent— 2,342 
Other2,826 2,599 
Total other noncurrent liabilities$9,859 $9,803 
v3.20.4
Leases (Tables)
 12 Months Ended
Dec. 31, 2020
Leases [Abstract]  
Components of Lease Costs
The components of lease cost related to the Company's operating leases included in the consolidated statements of operations were as follows:
Year Ended December 31,
2020
(in thousands)
Operating lease cost$19,544 
Sublease income(2,829)
Total lease cost$16,715 
Schedule of Lease Liability Maturities Maturities of the operating lease liabilities as of December 31, 2020 are as follows:
December 31, 2020
(in thousands)
2021$18,750 
202214,784 
20238,357 
20244,552 
2025557 
Thereafter92 
Total lease payments$47,092 
Less: Imputed interest$(2,066)
Total operating lease liabilities$45,026 
Schedule of Future Minimum Lease Payments under Prior Guidance
Prior to the Company's adoption of ASC 842, future minimum operating lease payments as of December 31, 2019 were as follows:
December 31, 2019
(in thousands)
2020$18,618 
202116,942 
202212,423 
20236,410 
20244,474 
Thereafter10,304 
Total lease payments$69,171 
v3.20.4
Debt (Tables)
 12 Months Ended
Dec. 31, 2020
Debt Disclosure [Abstract]  
Schedule of Convertible Debt
The net carrying amount of the liability component of the Notes was as follows:

December 31, 2020
(in thousands)
Principal$575,000 
Unamortized debt discount(184,674)
Unamortized debt issuance costs(7,051)
Carrying amount of the liability component, net$383,275 

The net carrying amount of the equity component of the Notes was as follows:
December 31, 2020
(in thousands)
Proceeds allocated to the conversion option (debt discount)$205,290 
Less: allocated issuance costs(4,478)
Carrying amount of the equity component, net$200,812 
Schedule of Interest Expense
The following table sets forth total interest expense recognized related to the Notes:
Year Ended December 31,
2020
(in thousands)
Coupon interest expense$2,707 
Amortization of debt discount20,616 
Amortization of debt issuance costs1,013 
Total$24,336 
v3.20.4
Commitment and Contingencies (Tables)
 12 Months Ended
Dec. 31, 2020
Commitments and Contingencies Disclosure [Abstract]  
Schedule of Purchase Commitments
Payments Due by Period as of December 31, 2020
Total20212022202320242025Thereafter
(in thousands)
Non-cancelable:
Open purchase agreements(1)
$17,621 $5,360 $4,626 $1,866 $741 $752 $4,276 
Bandwidth and other co-location related commitments(2)
36,797 14,420 11,769 5,294 2,194 2,086 1,034 
Other commitments(3)
2,187 2,187 — — — — — 
Total$56,605 $21,967 $16,395 $7,160 $2,935 $2,838 $5,310 
(1)Open purchase commitments are for the purchase of services under non-cancelable contracts. They were not recorded as liabilities on the consolidated balance sheet as of December 31, 2020 as the Company had not yet received the related services.
(2)Long-term commitments for bandwidth usage and other co-location related commitments with various networks and Internet service providers. The costs for services not yet received were not recorded as liabilities on the consolidated balance sheet as of December 31, 2020.
(3)Indemnity holdback consideration associated with the S2 acquisition. See Note 14.
v3.20.4
Common Stock (Tables)
 12 Months Ended
Dec. 31, 2020
Equity [Abstract]  
Schedule of Common Stock Reserved for Future Issuance
Shares of common stock reserved for future issuance, on an as-if converted basis, are as follows:
December 31,
20202019
(in thousands)
Convertible senior notes19,972 — 
Stock options issued and outstanding18,186 21,191 
Remaining shares available for issuance under the 2019 Plan24,539 29,048 
Outstanding and unsettled restricted stock units (RSUs)7,808 7,175 
Shares available for issuance under the ESPP5,230 5,870 
Total shares of common stock reserved75,735 63,284 
v3.20.4
Stock-based Compensation (Tables)
 12 Months Ended
Dec. 31, 2020
Share-based Payment Arrangement [Abstract]  
Schedule of Stock-based Awards
The following table summarizes the stock options activity under the 2010 Plan and 2019 Plan:
Stock Options Outstanding
(in thousands, except year and per share data)
Shares Subject
to Options
Outstanding		Weighted-
Average
Exercise Price
per Option		Weighted-
Average
Remaining
Contractual
Terms (in years)		Aggregate
Intrinsic Value
Balances as of December 31, 201728,127 $1.62 8.5$11,684 
Options granted10,527 $2.91 
Options exercised(12,387)$1.53 $15,433 
Repurchase of unvested shares— 
Options canceled/forfeited/expired(1,180)$2.24 
Balances as of December 31, 201825,087 $2.18 8.4$159,945 
Options granted394 $9.60 
Options exercised(2,665)$2.24 $22,306 
Repurchase of unvested shares— 
Options canceled/forfeited/expired(1,625)$2.35 
Balances as of December 31, 201921,191 $2.30 7.4$312,720 
Options granted 1,710 $18.05 
Options exercised (4,451)$1.73 $142,758 
Repurchase of unvested shares
Options canceled/forfeited/expired (264)$2.61 
Balances as of December 31, 202018,186 $3.92 7.0$1,310,650 
Vested and expected to vest as of December 31, 202018,186 $3.92 7.0$1,310,650 
Exercisable as of December 31, 202016,482 $2.47 6.8$1,211,809 
Schedule of Assumptions Used to Determine the Fair Value of Stock Options Granted The weighted-average assumptions used to determine the fair value of stock options granted during the periods presented were as follows:
Year ended December 31,
202020192018
Expected term (in years)6.06.26.5
Expected volatility40.3 %40.3 %43.5 %
Risk-free interest rate0.7 %2.3 %2.9 %
Dividend yield— — — 
Schedule of Restricted Stock Units Activity RSU activity for the year ended December 31, 2020 was as follows:
Restricted Stock and RSUsWeighted-Average
Grant
Date Fair Value
(in thousands, except per share data)
Unvested and outstanding as of December 31, 20196,508 $11.08 
Granted - RSUs4,153 $33.13 
Granted - Restricted stock949 $17.06 
Vested - RSUs(2,286)$11.80 
Vested - Restricted stock(107)$17.06 
Forfeited (588)$13.18 
Unvested as of December 31, 20208,629 $21.38 
Vested and not yet released21 $36.56 
Outstanding as of December 31, 20208,650 $21.41 
Schedule of Fair Value Assumptions for Employee Stock Purchase Plan
The weighted-average assumptions used to determine the fair value of the ESPP during the periods presented were as follows:
Year ended December 31,
20202019
Expected term (in years)0.50.7
Risk-free interest rate0.1 %1.8 %
Expected volatility63.1 %35.5 %
Dividend yield— — 
Schedule of Stock-based Compensation Expense
The following table sets forth the total stock-based compensation expense included in the Company’s consolidated statements of operations:
Year Ended December 31,
202020192018
(in thousands)
Cost of revenue$1,225 $716 $119 
Sales and marketing16,019 8,709 979 
Research and development26,090 13,037 1,532 
General and administrative13,000 14,165 24,717 
Total stock-based compensation expense$56,334 $36,627 $27,347 
v3.20.4
Net Loss per Share Attributable to Common Stockholders (Tables)
 12 Months Ended
Dec. 31, 2020
Earnings Per Share [Abstract]  
Schedule of Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders
The following table sets forth the computation of basic and diluted net loss per share attributable to common stockholders:

Year Ended December 31,

202020192018
Class AClass BClass AClass BCommon
(in thousands, except per share data)
Net loss attributable to common stockholders
$(70,955)$(48,415)$(18,259)$(87,569)$(87,164)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted
178,189 121,585 25,243 121,063 80,981 
Net loss per share attributable to common stockholders, basic and diluted
$(0.40)$(0.40)$(0.72)$(0.72)$(1.08)
Schedule of Potential Shares of Common Stock Excluded from Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders The potential shares of common stock that were excluded from the computation of diluted net loss per share attributable to common stockholders for the periods presented because including them would have been antidilutive are as follows:
December 31,
202020192018
(in thousands)
Convertible senior notes
15,363 — — 
Shares subject to repurchase
3,872 5,945 6,738 
Unexercised stock options
18,186 21,191 25,087 
Unvested restricted stock and RSUs
8,629 6,508 — 
Redeemable convertible preferred stock— — 165,658 
Redeemable convertible preferred stock warrants— — 177 
Vested and unreleased RSUs21 — — 
Shares issuable pursuant to the ESPP133 438 — 
Total
46,204 34,082 197,660 
v3.20.4
Income Taxes (Tables)
 12 Months Ended
Dec. 31, 2020
Income Tax Disclosure [Abstract]  
Components of Income (Loss) Before Income Taxes
The components of the Company's loss before income taxes for the years ended December 31, 2020, 2019, and 2018 were as follows:
Year Ended December 31,
202020192018
(in thousands)
Domestic$(143,320)$(117,401)$(87,615)
Foreign18,347 12,688 1,528 
Total loss before income taxes$(124,973)$(104,713)$(86,087)
Components of Provision for Income Taxes
The components of the Company's provision for (benefit from) income taxes for the years ended December 31, 2020, 2019, and 2018 were as follows:
Year Ended December 31,
202020192018
(in thousands)
Current expense:
Federal$488 $391 $402 
State66 29 42 
Foreign769 325 248 
Total current provision for income taxes$1,323 $745 $692 
Deferred expense (benefit):
Federal(641)— (1)
State(140)— — 
Foreign(6,145)370 386 
Total deferred provision for (benefit from) income taxes$(6,926)$370 $385 
Total provision for (benefit from) income taxes$(5,603)$1,115 $1,077 
Reconciliation of U.S. Federal Statutory Rate to Effective Tax Rate A reconciliation of the U.S. federal statutory rate to the Company's effective tax rate is as follows:
Year Ended December 31,
202020192018
Expected benefit at U.S. federal statutory rate21.0 %21.0 %21.0 %
State income taxes, net of federal tax benefits— — — 
Foreign income or losses taxed at different rates7.5 0.6 (1.3)
Stock-based compensation16.3 (1.2)(5.5)
Change in valuation allowance(39.4)(20.5)(14.0)
Withholding taxes(0.4)(0.4)(0.5)
Miscellaneous permanent items(0.5)(0.6)(1.0)
Total provision for (benefit from) income taxes4.5 %(1.1)%(1.3)%

In 2020, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets, offset by the partial release of the U.S. valuation allowance in connection with the acquisition of S2, excess tax benefits from stock-based compensation deductions in the United Kingdom, and income tax expense from profitable foreign jurisdictions. In 2019 and 2018, the difference in the Company's effective tax rate and the U.S. federal statutory tax rate was also primarily due to the recording of a full valuation allowance on the Company's U.S. deferred tax assets and income tax expense from profitable foreign jurisdictions.
Components of Deferred Tax Assets and Liabilities
The components of the Company's deferred tax assets and liabilities as of December 31, 2020 and 2019 were as follows:
Year Ended December 31,
20202019
(in thousands)
Deferred tax assets:
Net operating loss carryforwards$116,181 $53,536 
Tax credit carryforwards14,780 11,969 
Operating lease liabilities10,322 — 
Stock-based compensation10,118 6,852 
Accrued expenses and reserves2,615 1,988 
Depreciation and amortization4 85 
Other102 40 
Gross deferred tax assets154,122 74,470 
Valuation allowance(75,091)(63,487)
Total deferred tax assets$79,031 $10,983 
Deferred tax liabilities:
Convertible senior notes(43,889)— 
Right-of-use assets(10,626)— 
Deferred commissions(10,183)(5,487)
Capitalized internal-use software(7,405)(4,668)
Depreciation and amortization(1,326)(1,149)
Other(2)(225)
Total deferred tax liabilities$(73,431)$(11,529)
Net deferred tax assets (liabilities)$5,600 $(546)
Reconciliation of Gross Unrecognized Tax Benefits
A reconciliation of the beginning and ending amount of the Company's total gross unrecognized tax benefits was as follows:
Year Ended December 31,
202020192018
(in thousands)
Balance as of the beginning of the period$3,740 $2,549 $2,247 
Increases for tax positions related to the prior year396 — — 
Decreases for tax positions related to the prior year(303)(120)(613)
Additions for tax positions related to the current year1,849 1,311 915 
Balance as of the end of the period$5,682 $3,740 $2,549 
v3.20.4
Business Combinations (Tables)
 12 Months Ended
Dec. 31, 2020
Business Combinations [Abstract]  
Schedule of Assets Acquired and Liabilities Assumed
The fair values of assets acquired and liabilities assumed on the acquisition date are summarized as follows (in thousands):
Prepaid expenses and other current assets$6 
Developed technology5,600 
Goodwill13,084 
Total assets acquired18,690 
Accrued expenses and other current liabilities(208)
Other noncurrent liabilities(782)
Total purchase price$17,700 
v3.20.4
Segment and Geographic Information (Tables)
 12 Months Ended
Dec. 31, 2020
Segment Reporting [Abstract]  
Schedule of Property and Equipment, Net by Geographic Area
The Company’s property and equipment, net, by geographic area were as follows:
December 31,
20202019
(in thousands)
United States$79,078 $59,688 
Rest of the world44,610 41,778 
Total property and equipment, net$123,688 $101,466 
v3.20.4
Organization and Basis of Presentation (Details)
$ in Millions
 1 Months Ended
Sep. 30, 2019
USD ($)
Initial Public Offering | Class A common stock  
Class of Stock [Line Items]  
Aggregate proceeds received from initial public offering, net of underwriters' discounts and commissions $ 565.0
v3.20.4
Summary of Significant Accounting Policies - Narrative (Details)
 1 Months Ended 12 Months Ended
Jan. 01, 2020
USD ($)
Nov. 30, 2017
USD ($)
Dec. 31, 2020
USD ($)
segment
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
May 31, 2020
Dec. 31, 2017
USD ($)
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Amortization period     3 years        
Advertising expense     $ 25,000,000.0 $ 18,800,000 $ 10,400,000    
Foreign currency remeasurement loss     900,000 200,000 300,000    
Other-than-temporary impairment     0 0 0    
Goodwill impairment charges     0 0 0    
In-process research and development recognized   $ 300,000          
Impairment of intangible assets, finite-lived     $ 0 0 0    
Number of reportable segments | segment     1        
Number of operating segments | segment     1        
Operating lease right-of-use assets $ 50,000,000.0   $ 43,148,000 0      
Operating lease liability 52,800,000   45,026,000        
Derecognition of deferred rent 2,800,000            
Derecognition of build-to-suit lease 9,900,000   9,886,000 0 0    
Derecognition of lease financing obligation $ 10,500,000            
Period of adoption, adjustment     816,940,000 725,828,000 (113,505,000)   $ (59,834,000)
Cumulative Effect, Period of Adoption, Adjustment              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Period of adoption, adjustment       556,000      
Accumulated deficit              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Period of adoption, adjustment     $ (420,520,000) (301,706,000) $ (195,878,000)   $ (108,714,000)
Accumulated deficit | Cumulative Effect, Period of Adoption, Adjustment              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Period of adoption, adjustment       $ 556,000      
Convertible Debt              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Interest rate     0.75%     0.75%  
Minimum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Subscription and support term length     1 year        
Maximum              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Subscription and support term length     3 years        
Developed technology              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Estimated useful life     2 years        
Capitalized internal-use software              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Useful life     3 years        
Options              
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]              
Requisite service period of awards     4 years        
v3.20.4
Summary of Significant Accounting Policies - Schedule of Useful Lives of Property and Equipment (Details)
 12 Months Ended
Dec. 31, 2020
Servers—network infrastructure  
Property, Plant and Equipment [Line Items]  
Useful Lives 4 years
Buildings  
Property, Plant and Equipment [Line Items]  
Useful Lives 30 years
Office and computer equipment  
Property, Plant and Equipment [Line Items]  
Useful Lives 3 years
Office furniture  
Property, Plant and Equipment [Line Items]  
Useful Lives 3 years
Software  
Property, Plant and Equipment [Line Items]  
Useful Lives 3 years
v3.20.4
Revenue - Additional Information (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Revenue from Contract with Customer [Abstract]      
Revenue recognized $ 31,300,000 $ 16,800,000 $ 11,900,000
Impairment losses of deferred contract acquisition costs $ 0    
v3.20.4
Revenue - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Disaggregation of Revenue [Line Items]      
Revenue $ 431,059 $ 287,022 $ 192,674
Channel partners      
Disaggregation of Revenue [Line Items]      
Revenue 45,300 26,496 13,231
Direct customers      
Disaggregation of Revenue [Line Items]      
Revenue 385,759 260,526 179,443
United States      
Disaggregation of Revenue [Line Items]      
Revenue 218,191 144,575 92,652
Europe, Middle East, and Africa      
Disaggregation of Revenue [Line Items]      
Revenue 109,274 68,418 48,438
Asia Pacific      
Disaggregation of Revenue [Line Items]      
Revenue 76,177 55,131 38,851
Other      
Disaggregation of Revenue [Line Items]      
Revenue $ 27,417 $ 18,898 $ 12,733
Geographic Concentration Risk | Revenue      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 100.00% 100.00% 100.00%
Geographic Concentration Risk | Revenue | United States      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 51.00% 50.00% 48.00%
Geographic Concentration Risk | Revenue | Europe, Middle East, and Africa      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 25.00% 24.00% 25.00%
Geographic Concentration Risk | Revenue | Asia Pacific      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 18.00% 19.00% 20.00%
Geographic Concentration Risk | Revenue | Other      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 6.00% 7.00% 7.00%
Sales Channel Concentration Risk | Revenue      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 100.00% 100.00% 100.00%
Sales Channel Concentration Risk | Revenue | Channel partners      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 11.00% 9.00% 7.00%
Sales Channel Concentration Risk | Revenue | Direct customers      
Disaggregation of Revenue [Line Items]      
Percentage of revenue 89.00% 91.00% 93.00%
v3.20.4
Revenue - Deferred Contract Acquisition Costs (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Capitalized Contract Cost [Roll Forward]      
Beginning balance $ 25,184 $ 15,940 $ 10,765
Capitalization of contract acquisition costs 36,316 20,065 12,235
Amortization of deferred contract acquisition costs (17,324) (10,821) (7,060)
Ending balance $ 44,176 $ 25,184 $ 15,940
v3.20.4
Revenue - Remaining Performance Obligations (Details)
$ in Millions
Dec. 31, 2020
USD ($)
Revenue from Contract with Customer [Abstract]  
Remaining performance obligation, amount $ 383.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01  
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]  
Remaining performance obligation, percent 75.00%
Remaining performance obligation, expected timing of satisfaction 12 months
v3.20.4
Fair Value Measurements - Schedule of Cash and Available-for-sale Debt Securities' Amortized Cost, Unrealized Gains (Losses) and Fair Value by Significant Investment Category (Details) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost $ 108,895,000 $ 138,976,000
Amortized Cost 1,041,108,000 643,471,000
Unrealized Gain 270,000 190,000
Unrealized (Loss) (31,000) (53,000)
Fair Value 1,041,347,000 643,608,000
Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 22,114,000 24,631,000
Unrealized Gain 0 0
Unrealized (Loss) 0 0
Fair Value 22,114,000 24,631,000
Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Unrealized Gain 0 0
Unrealized (Loss) 0 0
Level I | Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 71,038,000 32,856,000
Unrealized Gain 0 0
Unrealized (Loss) 0 0
Fair Value 71,038,000 32,856,000
Level II    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 947,956,000 585,984,000
Unrealized Gain 270,000 190,000
Unrealized (Loss) (31,000) (53,000)
Fair Value 948,195,000 586,121,000
Level II | Corporate bonds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 169,324,000 84,054,000
Unrealized Gain 43,000 22,000
Unrealized (Loss) (26,000) (30,000)
Fair Value 169,341,000 84,046,000
Level II | U.S. treasury securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 576,652,000 311,083,000
Unrealized Gain 223,000 151,000
Unrealized (Loss) (4,000) (23,000)
Fair Value 576,871,000 311,211,000
Level II | U.S. government agency securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 15,617,000 95,380,000
Unrealized Gain 4,000 17,000
Unrealized (Loss) (1,000) 0
Fair Value 15,620,000 95,397,000
Level II | Commercial paper    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Amortized Cost 186,363,000 95,467,000
Unrealized Gain 0 0
Unrealized (Loss) 0 0
Fair Value 186,363,000 95,467,000
Cash & Cash Equivalents | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 108,895,000 138,976,000
Cash & Cash Equivalents | Fair Value, Recurring | Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 19,523,000 24,631,000
Cash & Cash Equivalents | Fair Value, Recurring | Level I | Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 64,378,000 26,196,000
Cash & Cash Equivalents | Fair Value, Recurring | Level II    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 24,994,000 88,149,000
Cash & Cash Equivalents | Fair Value, Recurring | Level II | Corporate bonds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Cash & Cash Equivalents | Fair Value, Recurring | Level II | U.S. treasury securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Cash & Cash Equivalents | Fair Value, Recurring | Level II | U.S. government agency securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 22,549,000
Cash & Cash Equivalents | Fair Value, Recurring | Level II | Commercial paper    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 24,994,000 65,600,000
Available-for-sale Securities | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 923,201,000 497,972,000
Available-for-sale Securities | Fair Value, Recurring | Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Available-for-sale Securities | Fair Value, Recurring | Level I | Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Available-for-sale Securities | Fair Value, Recurring | Level II    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 923,201,000 497,972,000
Available-for-sale Securities | Fair Value, Recurring | Level II | Corporate bonds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 169,341,000 84,046,000
Available-for-sale Securities | Fair Value, Recurring | Level II | U.S. treasury securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 576,871,000 311,211,000
Available-for-sale Securities | Fair Value, Recurring | Level II | U.S. government agency securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 15,620,000 72,848,000
Available-for-sale Securities | Fair Value, Recurring | Level II | Commercial paper    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 161,369,000 29,867,000
Long-term Restricted Cash | Fair Value, Recurring    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 9,251,000 6,660,000
Long-term Restricted Cash | Fair Value, Recurring | Cash    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 2,591,000 0
Long-term Restricted Cash | Fair Value, Recurring | Level I | Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 6,660,000 6,660,000
Long-term Restricted Cash | Fair Value, Recurring | Level II    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Long-term Restricted Cash | Fair Value, Recurring | Level II | Corporate bonds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Long-term Restricted Cash | Fair Value, Recurring | Level II | U.S. treasury securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Long-term Restricted Cash | Fair Value, Recurring | Level II | U.S. government agency securities    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value 0 0
Long-term Restricted Cash | Fair Value, Recurring | Level II | Commercial paper    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Fair Value $ 0 $ 0
v3.20.4
Fair Value Measurements - Narrative (Details) - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Restricted cash $ 6,660,000 $ 6,660,000
Amortized cost of available-for-sale investments with maturities less than one year 866,500,000 450,200,000
Amortized cost of available-for-sale investments with maturities greater than one year 56,500,000 47,700,000
Net unrealized gains (losses) on investments, net of tax 200,000 100,000
Convertible Debt    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Debt instrument, fair value 1,225,600,000  
Money market funds    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Unrealized gain 0 0
Unrealized loss $ 0 $ 0
v3.20.4
Balance Sheet Components - Activity in Allowance for Doubtful Accounts (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Accounts Receivable, Allowance for Credit Loss [Roll Forward]      
Beginning balance $ 533 $ 160 $ 0
Provision for bad debt 3,368 2,488 1,080
Write-off of uncollectible accounts receivable (2,198) (2,115) (920)
Ending balance $ 1,703 $ 533 $ 160
v3.20.4
Balance Sheet Components - Prepaid Expenses and Other Current Assets (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Prepaid expenses $ 13,689 $ 10,913
Deposits 4,246 2,773
Other 10,295 3,308
Total prepaid expenses and other current assets $ 28,230 $ 16,994
v3.20.4
Balance Sheet Components - Property and Equipment, Net (Details) - USD ($)
$ in Thousands
 12 Months Ended
Jan. 01, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Property, Plant and Equipment [Line Items]        
Gross property and equipment   $ 206,296 $ 168,655  
Less accumulated depreciation and amortization   (82,608) (67,189)  
Total property and equipment, net   123,688 101,466  
Depreciation and amortization expense   45,900 29,400 $ 18,400
Servers—network infrastructure        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   108,988 84,979  
Buildings        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   0 13,035  
Buildings | Accounting Standards Update 2016-02        
Property, Plant and Equipment [Line Items]        
Change in property and equipment for adoption of new ASU $ (13,000)      
Construction in progress        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   11,242 8,692  
Capitalized internal-use software        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   49,618 31,171  
Office and computer equipment        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   17,867 13,528  
Office furniture        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   5,657 6,124  
Software        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   1,808 1,025  
Leasehold improvements        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   10,686 9,870  
Leasehold improvements | Accounting Standards Update 2016-02        
Property, Plant and Equipment [Line Items]        
Change in property and equipment for adoption of new ASU $ 1,600      
Asset retirement obligation        
Property, Plant and Equipment [Line Items]        
Gross property and equipment   430 231  
Software        
Property, Plant and Equipment [Line Items]        
Depreciation and amortization expense   $ 12,600 $ 6,700 $ 3,300
v3.20.4
Balance Sheet Components - Goodwill (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Jan. 31, 2020
Business Acquisition [Line Items]        
Goodwill $ 17,167,000 $ 4,083,000    
Goodwill impairment charges 0 $ 0 $ 0  
S2 Systems Corporation        
Business Acquisition [Line Items]        
Goodwill       $ 13,084,000
Goodwill, acquired during period $ 13,100,000      
v3.20.4
Balance Sheet Components - Acquired Intangible Assets, Net (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]      
Gross Carrying Amount $ 5,600 $ 250  
Accumulated Amortization 2,800 219  
Net Book Value 2,800 31  
Amortization of acquired intangible assets 3,100 100 $ 500
2021 2,800    
Developed technology      
Finite-Lived Intangible Assets [Line Items]      
Gross Carrying Amount 5,600 250  
Accumulated Amortization 2,800 219  
Net Book Value 2,800 $ 31  
In-process research and development recognized $ 5,600    
v3.20.4
Balance Sheet Components - Accrued Expenses and Other Current Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Accrued compensation and benefits $ 25,410 $ 14,970
Accrued expenses 6,916 5,331
Customer refunds and credits 1,548 3,328
Accrued co-location and bandwidth 5,205 2,696
Other 6,548 1,989
Total accrued expenses and other current liabilities $ 45,627 $ 28,314
v3.20.4
Balance Sheet Components - Other Noncurrent Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Organization, Consolidation and Presentation of Financial Statements [Abstract]    
Accrued taxes $ 7,033 $ 4,862
Deferred rent 0 2,342
Other 2,826 2,599
Total other noncurrent liabilities $ 9,859 $ 9,803
v3.20.4
Leases - Narrative (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Lessee, Lease, Description [Line Items]    
Operating lease, remaining lease term 4 months 24 days  
Sublease income $ 2,829 $ 1,600
Lease not yet commenced, undiscounted amount $ 15,400  
Lease not yet commenced, term of contract 3 years 6 months  
Weighted average remaining lease term 2 years 9 months 18 days  
Operating lease, weighted average discount rate, percent 3.10%  
Rent expense   $ 11,200
Maximum    
Lessee, Lease, Description [Line Items]    
Operating lease, remaining lease term 4 years  
Maximum | Co-location Asset Lease    
Lessee, Lease, Description [Line Items]    
Operating lease, remaining lease term 5 years 7 months 6 days  
v3.20.4
Leases - Schedule of Lease Costs (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Leases [Abstract]    
Operating lease cost $ 19,544  
Sublease income (2,829) $ (1,600)
Total lease cost $ 16,715  
v3.20.4
Leases - Lease Liability Maturities (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Jan. 01, 2020
Leases [Abstract]    
2021 $ 18,750  
2022 14,784  
2023 8,357  
2024 4,552  
2025 557  
Thereafter 92  
Total lease payments 47,092  
Less: Imputed interest (2,066)  
Total operating lease liabilities $ 45,026 $ 52,800
v3.20.4
Leases - Future Minimum Payments Due Under Prior Guidance (Details)
$ in Thousands
Dec. 31, 2019
USD ($)
Leases [Abstract]  
2021 $ 18,618
2022 16,942
2023 12,423
2024 6,410
2025 4,474
Thereafter 10,304
Total lease payments $ 69,171
v3.20.4
Debt - Narrative (Details)
$ / shares in Units, shares in Millions
 1 Months Ended 12 Months Ended
May 31, 2020
USD ($)
$ / shares
Dec. 31, 2020
USD ($)
day
segment
$ / shares
shares
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Debt Instrument [Line Items]        
Gross proceeds from issuance of convertible senior notes $ 562,500,000 $ 575,000,000 $ 0 $ 0
Convertible debt, conversion ratio   0.0267187    
Conversion price (in dollars per share) | $ / shares   $ 37.43    
Convertible debt, equity component $ 205,300,000 $ 200,812,000    
Issuance cost, equity component   $ 0 $ 5,268,000 $ 0
Closing share price (in dollars per share) | $ / shares   $ 75.99    
If-converted value in excess of principal   $ 592,500,000    
Remaining life, convertible debt   53 months    
Shares covered by capped calls (in shares) | shares   15.4    
Purchases of capped calls related to convertible senior notes   $ 67,333,000    
Class A common stock        
Debt Instrument [Line Items]        
Capped call, initial strike price (in dollars per share) | $ / shares $ 37.43      
Capped call, initial cap price (in dollars per share) | $ / shares $ 57.58      
Scenario One        
Debt Instrument [Line Items]        
Conversion requirement, threshold trading days | day   20    
Conversion requirement, threshold consecutive trading days | day   30    
Conversion requirement, threshold percentage of stock price trigger   130.00%    
Scenario Two        
Debt Instrument [Line Items]        
Conversion requirement, threshold consecutive trading days | day   5    
Conversion requirement, threshold percentage of stock price trigger   98.00%    
Conversion requirement, threshold business days following consecutive trading days | day   5    
Scenario Three        
Debt Instrument [Line Items]        
Conversion requirement, threshold trading days | segment   20    
Conversion requirement, threshold consecutive trading days | day   30    
Conversion requirement, threshold percentage of stock price trigger   130.00%    
Convertible Debt        
Debt Instrument [Line Items]        
Face amount $ 575,000,000.0      
Face amount, additional principal issuable $ 75,000,000.0      
Interest rate 0.75% 0.75%    
Issuance cost, liability component $ 8,000,000.0      
Issuance cost, equity component $ 4,500,000      
Convertible Debt | Measurement Input Effective Interest Rate        
Debt Instrument [Line Items]        
Measurement input 0.100      
Convertible Debt | Scenario Three        
Debt Instrument [Line Items]        
Redemption price, percentage   100.00%    
Convertible Debt | Scenario Four, Fundamental Change        
Debt Instrument [Line Items]        
Redemption price, percentage   100.00%    
v3.20.4
Debt - Liability Component (Details) - Convertible Debt
$ in Thousands
Dec. 31, 2020
USD ($)
Debt Instrument [Line Items]  
Principal $ 575,000
Unamortized debt discount (184,674)
Unamortized debt issuance costs (7,051)
Carrying amount of the liability component, net $ 383,275
v3.20.4
Debt - Equity Component (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
May 31, 2020
Debt Disclosure [Abstract]    
Proceeds allocated to the conversion option (debt discount) $ 205,290  
Less: allocated issuance costs (4,478)  
Carrying amount of the equity component, net $ 200,812 $ 205,300
v3.20.4
Debt - Schedule of Interest Components (Details)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
USD ($)
Debt Disclosure [Abstract]  
Coupon interest expense $ 2,707
Amortization of debt discount 20,616
Amortization of debt issuance costs 1,013
Total $ 24,336
v3.20.4
Commitment and Contingencies - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Commitments and Contingencies Disclosure [Abstract]      
Cost and expenses related to bandwidth and other co-location commitments $ 51.4 $ 37.0 $ 27.5
v3.20.4
Commitment and Contingencies - Schedule of Purchase Commitments (Details)
$ in Thousands
Dec. 31, 2020
USD ($)
Open Purchase Agreements  
Total payments due, open purchase agreements $ 17,621
2021 5,360
2022 4,626
2023 1,866
2024 741
2025 752
Thereafter 4,276
Bandwidth and Co-Location Commitments  
Total payments due, bandwidth and co-location commitments 36,797
2021 14,420
2022 11,769
2023 5,294
2024 2,194
2025 2,086
Thereafter 1,034
Other Commitments  
Total payments due, other commitments 2,187
2021 2,187
2022 0
2023 0
2024 0
2025 0
Thereafter 0
Total Purchase Commitments  
Total payments due, purchase commitments 56,605
2021 21,967
2022 16,395
2023 7,160
2024 2,935
2025 2,838
Thereafter $ 5,310
v3.20.4
Preferred Stock (Details)
Dec. 31, 2020
$ / shares
shares
Equity [Abstract]  
Preferred stock, shares authorized (in shares) | shares 225,000,000
Preferred stock, par value (in dollars per share) | $ / shares $ 0.001
v3.20.4
Common Stock - Narrative (Details)
Dec. 31, 2020
vote
$ / shares
shares
Dec. 31, 2019
$ / shares
shares
Class A common stock    
Class of Stock [Line Items]    
Common stock, number of votes per share | vote 1  
Common stock, shares authorized (in shares) 2,250,000,000 2,250,000,000
Common stock, par value (in dollars per share) | $ / shares $ 0.001 $ 0.001
Common stock, shares issued (in shares) 249,401,232 87,071,783
Common stock, shares outstanding (in shares) 249,401,232 87,071,783
Class B common stock    
Class of Stock [Line Items]    
Common stock, number of votes per share | vote 10  
Common stock, shares authorized (in shares) 315,000,000 315,000,000
Common stock, par value (in dollars per share) | $ / shares $ 0.001 $ 0.001
Common stock, shares issued (in shares) 59,238,742 213,101,364
Common stock, shares outstanding (in shares) 59,238,742 213,101,364
v3.20.4
Common Stock - Schedule of Common Stock Reserved for Future Issuance (Details) - shares
shares in Thousands
Dec. 31, 2020
Dec. 31, 2019
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 75,735 63,284
Equity Incentive Plan, 2019    
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 24,539 29,048
Options    
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 18,186 21,191
Restricted Stock Units (RSUs)    
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 7,808 7,175
Shares issuable pursuant to the ESPP    
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 5,230 5,870
Convertible Debt    
Class of Stock [Line Items]    
Shares of common stock reserved (in shares) 19,972 0
v3.20.4
Stock-based Compensation - Narrative (Details) - USD ($)
 1 Months Ended 3 Months Ended 12 Months Ended
Sep. 30, 2019
Mar. 31, 2020
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Total grant date fair value for vested options     $ 7,300,000 $ 5,200,000 $ 3,400,000
Stock-based compensation expense     $ 56,334,000 $ 36,627,000 $ 27,347,000
Shares of common stock reserved (in shares)     75,735,000 63,284,000  
S2 Systems Corporation          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Issuance of common stock in connection with acquisition (in shares)     948,000    
Class A common stock | 2019 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Number of shares authorized for issuance (in shares)     66,661,953    
Number of new shares authorized for issuance (in shares)     29,335,000    
Number of additional shares authorized for issuance (in shares)     37,326,953    
Number of shares available for issuance (in shares)     24,538,422    
Class A and Class B Common Stock | 2019 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Potential increase in number of shares authorized, as a percentage of total common stock outstanding     5.00%    
Options          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average grant date fair value for options granted (in dollars per share)     $ 9.74 $ 4.10 $ 1.38
Unvested options exercisable (in shares)     10,765,894 15,477,903  
Options unrecognized stock-based compensation expense     $ 20,600,000 $ 15,800,000  
Weighted-average remaining vesting period     2 years 7 months 6 days 2 years 8 months 12 days  
Liability for early exercise of stock options     $ 8,600,000 $ 13,300,000  
Number of unvested shares expected to be repurchased (in shares)     3,871,772 5,945,083  
Shares of common stock reserved (in shares)     18,186,000 21,191,000  
Options | 2010 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     4 years    
Expiration period     10 years    
Options | Common Stock | 2010 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Exercise price of common stock, percentage of fair market value     100.00%    
Options | Class A common stock | 2019 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Cumulative shares granted (in shares)     1,710,189    
Restricted Stock Units (RSUs)          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     4 years    
Weighted-average remaining vesting period   2 years 6 months 3 years 6 months    
Stock-based compensation expense     $ 39,600,000 $ 24,900,000 $ 0
Unrecognized stock-based compensation expense     141,800,000 53,100,000  
Total grant date fair value for vested shares     $ 27,000,000.0 $ 6,000,000.0 $ 0
Shares of common stock reserved (in shares)     7,808,000 7,175,000  
Restricted Stock Units (RSUs) | Class A common stock | 2019 Equity Incentive Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Cumulative shares granted (in shares)     4,152,972    
Restricted Stock | S2 Systems Corporation          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Issuance of unvested restricted stock in connection with acquisition (in shares)     841,000    
Restricted stock issued in connection with acquisition, aggregate grant date fair value     $ 1,800,000 $ 0  
Stock-based compensation expense     5,600,000 0  
Unrecognized stock-based compensation expense     $ 8,800,000 $ 0  
Restricted Stock | Tranche One | S2 Systems Corporation          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     2 years    
Vesting percentage     77.80%    
Restricted Stock | Tranche Two | S2 Systems Corporation          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Vesting period     3 years    
ESPP          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares of common stock reserved (in shares)     5,230,000 5,870,000  
ESPP | 2019 Employee Stock Purchase Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Weighted-average remaining vesting period     4 months 24 days    
Unrecognized stock-based compensation expense     $ 2,000,000.0 $ 1,000,000.0  
Maximum ownership percentage threshold for participation 5.00%        
Maximum contribution percentage per employee 10.00%        
ESPP | Class A common stock | 2019 Employee Stock Purchase Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Shares of common stock reserved (in shares) 5,870,000        
Number of additional shares allowable under the plan (in shares) 5,870,000        
Purchase price of common stock, percentage of fair value 85.00%        
Offering period 6 months        
Purchase period 6 months        
Maximum number of shares available for repurchase for each employee (in shares) 1,500        
Maximum value of shares available for repurchase for each employee $ 25,000        
Number of shares repurchased (in shares)     639,773    
ESPP | Class A and Class B Common Stock | 2019 Employee Stock Purchase Plan          
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]          
Potential increase in number of share authorized, as a percentage of total common stock outstanding 1.00%        
v3.20.4
Stock-based Compensation - Schedule of Stock-based Awards (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Dec. 31, 2017
Shares Subject to Options Outstanding        
Stock options outstanding, beginning balance (in shares) 21,191 25,087 28,127  
Stock options granted (in shares) 1,710 394 10,527  
Stock options exercised (in shares) (4,451) (2,665) (12,387)  
Repurchases of unvested shares (in shares) 0 0  
Stock options cancelled, forfeited, expired (in shares) (264) (1,625) (1,180)  
Stock options outstanding, ending balance (in shares) 18,186 21,191 25,087 28,127
Stock options vested and expected to vest (in shares) 18,186      
Stock options exercisable (in shares) 16,482      
Weighted- Average Exercise Price per Option        
Stock options outstanding, weighted-average exercise price, beginning balance (in dollars per share) $ 2.30 $ 2.18 $ 1.62  
Stock options granted, weighted-average exercise price (in dollars per share) 18.05 9.60 2.91  
Stock options exercised, weighted-average exercise price (in dollars per share) 1.73 2.24 1.53  
Stock options cancelled, forfeited, expired, weighted-averaged exercise price (in dollars per share) 2.61 2.35 2.24  
Stock options outstanding, weighted-average exercise price, ending balance (in dollars per share) 3.92 $ 2.30 $ 2.18 $ 1.62
Stock options vested and expected to vest, weighted-average exercise price (in dollars per share) 3.92      
Stock options exercisable, weighted-average exercise price (in dollars per share) $ 2.47      
Weighted- Average Remaining Contractual Terms (in years)        
Stock options outstanding, weighted-average remaining contractual term 7 years 7 years 4 months 24 days 8 years 4 months 24 days 8 years 6 months
Stock options vested and expected to vest, weighted-average remaining contractual term 7 years      
Stock options exercisable, weighted-average remaining contractual term 6 years 9 months 18 days      
Aggregate Intrinsic Value        
Stock options outstanding, aggregate intrinsic value $ 1,310,650 $ 312,720 $ 159,945 $ 11,684
Stock options exercised, aggregate intrinsic value 142,758 $ 22,306 $ 15,433  
Stock options vested and expected to vest, aggregate intrinsic value 1,310,650      
Stock options exercisable, aggregate intrinsic value $ 1,211,809      
v3.20.4
Stock-based Compensation - Schedule of Assumptions Used to Determine the Fair Value of Stock Options Granted (Details) - Options
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]      
Expected term (in years) 6 years 6 years 2 months 12 days 6 years 6 months
Expected volatility 40.30% 40.30% 43.50%
Risk-free interest rate 0.70% 2.30% 2.90%
Dividend yield 0.00% 0.00% 0.00%
v3.20.4
Stock-based Compensation - Schedule of Restricted Stock Units Activity (Details)
shares in Thousands
 12 Months Ended
Dec. 31, 2020
$ / shares
shares
Restricted Stock and Restricted Stock Units  
Restricted Stock and RSUs  
Unvested and outstanding, beginning balance (in shares) | shares 6,508
Forfeited (in shares) | shares (588)
Unvested, ending balance (in shares) | shares 8,629
Vested and not yet released (in shares) | shares 21
Outstanding at end of period (in shares) | shares 8,650
Weighted-Average Grant Date Fair Value  
Unvested, weighted average grant date fair value, beginning balance (in dollars per share) | $ / shares $ 11.08
Forfeited (in dollars per share) | $ / shares 13.18
Unvested, weighted average grant date fair value, ending balance (in dollars per share) | $ / shares 21.38
Vested and not yet released, weighted-average grant date fair value (in dollars per share) | $ / shares 36.56
Outstanding at end of period, weighted-average grant date fair value (in dollars per share) | $ / shares $ 21.41
Restricted Stock Units (RSUs)  
Restricted Stock and RSUs  
Granted (in shares) | shares 4,153
Vested (in shares) | shares (2,286)
Weighted-Average Grant Date Fair Value  
Granted (in dollars per share) | $ / shares $ 33.13
Vested (in dollars per share) | $ / shares $ 11.80
Restricted Stock  
Restricted Stock and RSUs  
Granted (in shares) | shares 949
Vested (in shares) | shares (107)
Weighted-Average Grant Date Fair Value  
Granted (in dollars per share) | $ / shares $ 17.06
Vested (in dollars per share) | $ / shares $ 17.06
v3.20.4
Stock-based Compensation - Schedule of Fair Value Assumptions for Employee Stock Purchase Plan (Details) - ESPP
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]    
Expected term (in years) 6 months 8 months 12 days
Risk-free interest rate 0.10% 1.80%
Expected volatility 63.10% 35.50%
Dividend yield 0.00% 0.00%
v3.20.4
Stock-based Compensation - Schedule of Stock-based Compensation Expense (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]      
Total stock-based compensation expense $ 56,334 $ 36,627 $ 27,347
Cost of revenue      
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]      
Total stock-based compensation expense 1,225 716 119
Sales and marketing      
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]      
Total stock-based compensation expense 16,019 8,709 979
Research and development      
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]      
Total stock-based compensation expense 26,090 13,037 1,532
General and administrative      
Share-based Payment Arrangement, Expensed and Capitalized, Amount [Line Items]      
Total stock-based compensation expense $ 13,000 $ 14,165 $ 24,717
v3.20.4
Net Loss per Share Attributable to Common Stockholders - Schedule of Computation of Basic and Diluted Earnings per Share Attributable to Common Stockholders (Details) - USD ($)
$ / shares in Units, shares in Thousands, $ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]      
Net loss attributable to common stockholders $ (119,370) $ (105,828) $ (87,164)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares) 299,774 146,306 80,981
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share) $ (0.40) $ (0.72) $ (1.08)
Common Stock      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]      
Net loss attributable to common stockholders     $ (87,164)
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)     80,981
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)     $ (1.08)
Class A common stock | Common Stock      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]      
Net loss attributable to common stockholders $ (70,955) $ (18,259)  
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares) 178,189 25,243  
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share) $ (0.40) $ (0.72)  
Class B common stock | Common Stock      
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]      
Net loss attributable to common stockholders $ (48,415) $ (87,569)  
Weighted-average shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares) 121,585 121,063  
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share) $ (0.40) $ (0.72)  
v3.20.4
Net Loss per Share Attributable to Common Stockholders - Schedule of Potential Shares of Common Stock Excluded from Computation of Basic and Diluted Net Loss per Share Attributable to Common Stockholders (Details) - shares
shares in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 46,204 34,082 197,660
Convertible senior notes      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 15,363 0 0
Shares subject to repurchase      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 3,872 5,945 6,738
Unexercised stock options      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 18,186 21,191 25,087
Unvested restricted stock and RSUs      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 8,629 6,508 0
Redeemable convertible preferred stock      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 0 0 165,658
Redeemable convertible preferred stock warrants      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 0 0 177
Vested and unreleased RSUs      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 21 0 0
Shares issuable pursuant to the ESPP      
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]      
Potential shares of common stock excluded from computation of diluted net loss per share attributable to common stockholders (in shares) 133 438 0
v3.20.4
Income Taxes - Components of Income (Loss) Before Income Taxes (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Tax Disclosure [Abstract]      
Domestic $ (143,320) $ (117,401) $ (87,615)
Foreign 18,347 12,688 1,528
Loss before income taxes $ (124,973) $ (104,713) $ (86,087)
v3.20.4
Income Taxes - Components of Provision for Income Taxes (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Current expense:      
Federal $ 488 $ 391 $ 402
State 66 29 42
Foreign 769 325 248
Total current provision for income taxes 1,323 745 692
Deferred expense (benefit):      
Federal (641) 0 (1)
State (140) 0 0
Foreign (6,145) 370 386
Total deferred provision for (benefit from) income taxes (6,926) 370 385
Total provision for (benefit from) income taxes $ (5,603) $ 1,115 $ 1,077
v3.20.4
Income Taxes - Reconciliation of Effective Tax Rate (Details)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Tax Disclosure [Abstract]      
Expected benefit at U.S. federal statutory rate 21.00% 21.00% 21.00%
State income taxes, net of federal tax benefits 0.00% 0.00% 0.00%
Foreign income or losses taxed at different rates 7.50% 0.60% (1.30%)
Stock-based compensation 16.30% (1.20%) (5.50%)
Change in valuation allowance (39.40%) (20.50%) (14.00%)
Withholding taxes (0.40%) (0.40%) (0.50%)
Miscellaneous permanent items (0.50%) (0.60%) (1.00%)
Total provision for (benefit from) income taxes 4.50% (1.10%) (1.30%)
v3.20.4
Income Taxes - Components of Deferred Tax Assets and Liabilities (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Deferred tax assets:    
Net operating loss carryforwards $ 116,181 $ 53,536
Tax credit carryforwards 14,780 11,969
Operating lease liabilities 10,322 0
Stock-based compensation 10,118 6,852
Accrued expenses and reserves 2,615 1,988
Depreciation and amortization 4 85
Other 102 40
Gross deferred tax assets 154,122 74,470
Valuation allowance (75,091) (63,487)
Total deferred tax assets 79,031 10,983
Deferred tax liabilities:    
Convertible senior notes (43,889) 0
Right-of-use assets (10,626) 0
Deferred commissions (10,183) (5,487)
Capitalized internal-use software (7,405) (4,668)
Depreciation and amortization (1,326) (1,149)
Other (2) (225)
Deferred tax assets, net 5,600  
Total deferred tax liabilities $ (73,431) (11,529)
Net deferred tax assets (liabilities)   $ (546)
v3.20.4
Income Taxes - Narrative (Details) - USD ($)
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Income Tax Contingency [Line Items]      
Valuation allowance $ 75,091,000 $ 63,487,000  
Increase (decrease) in valuation allowance 11,600,000 25,600,000 $ 15,500,000
Amount of unrecognized tax benefits that would impact the effective income tax rate 100,000    
Amount of unrecognized tax benefits that would impact deferred tax assets 5,600,000    
Income tax expense related to interest and penalties 0 0 $ 0
Federal      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 448,700,000 221,500,000  
Federal | Research and development tax credit carryforward      
Income Tax Contingency [Line Items]      
Tax credit carryforwards 8,200,000    
State      
Income Tax Contingency [Line Items]      
Net operating loss carryforwards 215,800,000 104,700,000  
State | Research and development tax credit carryforward      
Income Tax Contingency [Line Items]      
Tax credit carryforwards 6,000,000.0    
Foreign      
Income Tax Contingency [Line Items]      
Tax credit carryforwards $ 1,800,000 $ 1,800,000  
v3.20.4
Income Taxes - Reconciliation of Gross Unrecognized Tax Benefits (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]      
Balance as of the beginning of the period $ 3,740 $ 2,549 $ 2,247
Increases for tax positions related to the prior year 396 0 0
Decreases for tax positions related to the prior year (303) (120) (613)
Additions for tax positions related to the current year 1,849 1,311 915
Balance as of the end of the period $ 5,682 $ 3,740 $ 2,549
v3.20.4
Business Combinations - Narrative (Details) - USD ($)
$ in Millions
 1 Months Ended 12 Months Ended
Jan. 31, 2020
Dec. 31, 2020
Business Acquisition [Line Items]    
Repayments of notes payable   $ 0.2
S2 Systems Corporation    
Business Acquisition [Line Items]    
Consideration transferred $ 17.7  
Cash payments to acquire business 13.7  
Cash acquired 0.1  
Value of shares issued 1.8  
Consideration held back $ 2.2  
Consideration holdback period 18 months  
Payments to settle acquiree's outstanding debt $ 6.9  
Compensation arrangements value 20.3  
Compensation arrangement with individual, compensation expense $ 5.7 5.7
Compensation arrangement with individual, recorded liability   $ 8.9
Compensation arrangement, weighted-average remaining recognition period   2 years 2 months 12 days
Estimated useful life 2 years  
Purchase accounting adjustment   $ 0.8
v3.20.4
Business Combinations Schedule of Assets Acquired and Liabilities Assumed (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Jan. 31, 2020
Dec. 31, 2019
Business Acquisition [Line Items]      
Goodwill $ 17,167   $ 4,083
S2 Systems Corporation      
Business Acquisition [Line Items]      
Prepaid expenses and other current assets   $ 6  
Developed technology   5,600  
Goodwill   13,084  
Total assets acquired   18,690  
Accrued expenses and other current liabilities   (208)  
Other noncurrent liabilities   (782)  
Total purchase price   $ 17,700  
v3.20.4
Segment and Geographic Information - Schedule of Property and Equipment, Net by Geographic Area (Details) - USD ($)
$ in Thousands
Dec. 31, 2020
Dec. 31, 2019
Segment Reporting Information [Line Items]    
Property and equipment, net $ 123,688 $ 101,466
United States    
Segment Reporting Information [Line Items]    
Property and equipment, net 79,078 59,688
Rest of the world    
Segment Reporting Information [Line Items]    
Property and equipment, net $ 44,610 $ 41,778