Equity Incentive Plans (Tables)

9 Months Ended

Sep. 30, 2021

Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]

Summary of Changes in Shares Available for Grant

Changes in shares available for grant during the nine months ended September 30, 2021 were as follows:

	Shares Available for Grant
Shares available for grant at December 31, 2020		18,617,001
2019 Equity Incentive Plan reserve increase effective January 1, 2021		6,882,344
Options and restricted stock units granted		(3,295,903	)
Options and restricted stock units forfeited, cancelled or expired		807,623
Shares available for grant at September 30, 2021		23,011,065

Summary of Stock Option Activity Under 2009 Plan and 2019 Plan

Stock option activity under the 2009 Plan and 2019 Plan during the nine months ended September 30, 2021 was as follows:

	Shares Subject to Outstanding Options			Weighted-Average Exercise Price per Share		Aggregate Intrinsic Value (in thousands)
Options outstanding at December 31, 2020		14,433,560		$	12.82	$	668,458
Options granted		2,407,629			41.21
Options forfeited or cancelled		(744,501	)		24.48
Options expired		(21,452	)		18.98
Options exercised		(3,310,804	)		7.04
Options outstanding at September 30, 2021		12,764,432		$	18.98	$	218,168
Options vested and exercisable at September 30, 2021		7,080,906		$	10.29	$	170,535

Summary of Restricted Stock Unit Activity

Restricted stock unit activity under the 2019 Plan during the nine months ended September 30, 2021 was as follows:

	Restricted Stock Units Outstanding			Weighted-Average Grant Date Fair Value per Share
Nonvested outstanding restricted stock units at December 31, 2020		50,000		$	28.10
Restricted stock units granted		888,274			40.21
Restricted stock units forfeited or cancelled		(41,670	)		45.06
Restricted stock units vested		(15,625	)		28.10
Nonvested outstanding restricted stock units at September 30, 2021		880,979		$	39.51

Summary of Estimated Grant Date Fair Value of Options Granted

The estimated grant date fair value of options granted during the nine months ended September 30, 2021 and 2020 was estimated using the Black-Scholes option-pricing model with the following assumptions:

	Nine Months Ended September 30,
	2021		2020
Fair value of common stock	$30.86 - $66.50		$17.68 - $48.54
Expected term (in years)	5.27 - 6.08		5.27 - 6.08
Risk-free interest rate	0.5% - 1.1%		0.4% - 1.7%
Expected volatility	67.1% - 70.0%		70.5% - 73.0%
Expected dividend yield		—		—

Summary of Compensation Costs Related to Stock Options and RSUs Included on Unaudited Condensed Consolidated Statements of Operations

The compensation costs related to stock options and restricted stock units for the three and nine months ended September 30, 2021 and 2020, respectively, are included on our unaudited condensed consolidated statements of operations as follows (in thousands):

	Three Months Ended September 30,				Nine Months Ended September 30,
	2021		2020		2021		2020
Cost of revenue	$	650	$	206	$	1,386	$	587
Research and development		3,637		2,216		10,311		5,912
Sales and marketing		3,369		1,759		9,166		4,583
General and administrative		3,987		2,289		10,513		6,436
Total share-based compensation expense	$	11,643	$	6,470	$	31,376	$	17,518