Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2021	Jul. 31, 2020	Jul. 31, 2021	Jul. 31, 2020
Income Statement [Abstract]
Revenue	$ 45,750	$ 20,674	$ 83,145	$ 38,631
Cost of revenue	18,788	7,543	37,071	15,156
Gross profit	26,962	13,131	46,074	23,475
Operating expenses:
Research and development	31,037	13,476	58,857	27,341
Sales and marketing	40,970	16,302	77,150	34,053
General and administrative	22,110	5,914	38,834	10,871
Total operating expenses	94,117	35,692	174,841	72,265
Loss from operations	(67,155)	(22,561)	(128,767)	(48,790)
Interest income	21	46	44	196
Interest expense	(479)	(477)	(782)	(777)
Other income (expense), net	(373)	182	(966)	(11)
Loss before provision for income taxes	(67,986)	(22,810)	(130,471)	(49,382)
Provision for income taxes	177	128	326	194
Net loss	$ (68,163)	$ (22,938)	$ (130,797)	$ (49,576)
Net loss per share attributable to Class A and Class B common stockholders, basic (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)
Net loss per share attributable to Class A and Class B common stockholders, diluted (in USD per share)	$ (0.57)	$ (0.67)	$ (1.59)	$ (1.45)