CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2021	Jan. 31, 2020	Jan. 31, 2019
Income Statement [Abstract]
Revenue	$ 592,049	$ 264,748	$ 96,666
Cost of revenue	242,588	116,557	51,753
Gross profit	349,461	148,191	44,913
Sales and marketing	479,317	293,577	125,642
Research and development	237,946	105,160	68,681
General and administrative	176,135	107,542	36,055
Total operating expenses	893,398	506,279	230,378
Operating loss	(543,937)	(358,088)	(185,465)
Interest income	7,507	11,551	8,759
Other expense, net	(610)	(1,005)	(502)
Loss before income taxes	(537,040)	(347,542)	(177,208)
Provision for income taxes	2,062	993	820
Net loss	$ (539,102)	$ (348,535)	$ (178,028)
Net loss per share attributable to Class A and Class B common stockholders - basic and diluted (in dollars per share)	$ (3.81)	$ (7.77)	$ (4.67)
Weighted-average shares used in computing net loss per share attributable to Class A and Class B common stockholders - basic and diluted (in shares)	141,613,196	44,847,442	38,162,228