Consolidated Statements of Operations and Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Jan. 31, 2020	Jan. 31, 2019	Jan. 31, 2018
Income Statement [Abstract]
Revenue	$ 298,829	$ 228,283	$ 170,201
Cost of revenue	77,030	57,413	44,095
Gross profit	221,799	170,870	126,106
Operating expenses:
Sales and marketing	218,076	158,845	126,980
Research and development	49,445	36,098	25,687
General and administrative	77,231	51,572	40,079
Total operating expenses	344,752	246,515	192,746
Loss from operations	(122,953)	(75,645)	(66,640)
Interest income	4,099	1,711	1,135
Interest expense	(308)	(143)	(359)
Other expense, net	(1,285)	(538)	(539)
Loss from operations before income taxes	(120,447)	(74,615)	(66,403)
(Provision for) benefit from income taxes	(1,097)	(222)	(162)
Net loss	$ (121,544)	$ (74,837)	$ (66,565)
Net loss per share attributable to common stockholders, basic and diluted (in dollars per share)	$ (1.09)	$ (0.76)	$ (0.85)
Weighted-average number of shares used in computing net loss per share attributable to common stockholders, basic and diluted (in shares)	111,758,946	98,387,366	78,632,448
Other comprehensive income (loss):
Foreign currency translation adjustment	$ 1,197	$ (75)	$ 492
Unrealized (loss) gain on marketable securities, net	(129)	280	(320)
Total comprehensive loss	$ (120,476)	$ (74,632)	$ (66,393)