Stock-Based Compensation

3 Months Ended

Mar. 31, 2022

Share-based Payment Arrangement [Abstract]

Stock-based compensation expense is included in the following line items in the condensed consolidated statements of operations (in thousands):


	Three Months Ended March 31,
	2022		2021
Sales and marketing	$	1,058	$	808
General and administrative	3,235		2,080
Research and development	7,817		5,000
Total stock-based compensation expense	$	12,110	$	7,888

The following table summarizes the components of non-cash stock-based compensation expense (in thousands):


	Three Months Ended March 31,
	2022		2021
Stock options and assumed options	$	778	$	617
Restricted stock units	11,284		7,224
Employee stock purchase plan	48		47
Total stock-based compensation expense	$	12,110	$	7,888
Tax windfall benefit from stock-based awards	$	529	$	2,560

We granted no stock options pursuant to our 2015 Equity Incentive Plan, or the 2015 Plan, during the three months ended March 31, 2022 and March 31, 2021. There were 14,020 stock options exercised during the three months ended March 31, 2022, as compared to 73,175 stock options for the same period in the prior year. There was an aggregate of 156,543 restricted stock units without performance conditions granted to certain of our employees, during the three months ended March 31, 2022, as compared to an aggregate of 127,216 restricted stock units without performance conditions for the same period in the prior year. There was an aggregate of 71,934 restricted stock units with performance conditions granted to certain of our employees during the three months ended March 31, 2022, as compared to no restricted stock units with performance conditions for the same period in the prior year. There were 57,497 restricted stock units without performance conditions that vested during the three months ended March 31, 2022, as compared to 69,370 restricted stock units without performance conditions vested during the same period in the prior year. There were no restricted stock units with performance conditions that vested during the three months ended March 31, 2022, as compared to 20,000 restricted stock units with performance conditions for the same period in the prior year.