CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2019	Jul. 31, 2018
Income Statement [Abstract]
Revenue	$ 145,826	$ 74,526	$ 267,814	$ 134,596
Cost of revenue	27,900	12,973	52,004	24,633
Gross profit	117,926	61,553	215,810	109,963
Operating expenses:
Research and development	15,054	7,049	28,837	13,313
Sales and marketing	79,652	41,054	143,693	77,315
General and administrative	20,955	10,028	39,458	17,597
Total operating expenses	115,661	58,131	211,988	108,225
Income from operations	2,265	3,422	3,822	1,738
Interest income, net	2,864	463	3,522	899
Other income, net	1,628	81	1,943	86
Net income before provision for income taxes	6,757	3,966	9,287	2,723
Provision for income taxes	(1,216)	(141)	(1,532)	(238)
Net income	5,541	3,825	7,755	2,485
Undistributed earnings attributable to participating securities	(20)	(3,329)	(2,794)	(2,485)
Net income attributable to common stockholders	$ 5,521	$ 496	$ 4,961	$ 0
Earnings Per Share [Abstract]
Basic (in dollars per share)	$ 0.02	$ 0.01	$ 0.03	$ 0.00
Diluted (in dollars per share)	$ 0.02	$ 0.00	$ 0.02	$ 0.00
Weighted-average shares used in computing net income per share attributable to common stockholders:
Basic (in shares)	271,813,141	83,330,741	192,130,510	81,999,734
Diluted (in shares)	292,185,665	108,454,323	215,774,619	107,584,379