CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Income Statement [Abstract]
Revenue	$ 166,593	$ 90,121	$ 434,407	$ 224,717
Cost of revenue	30,845	16,843	82,849	41,476
Gross profit	135,748	73,278	351,558	183,241
Operating expenses:
Research and development	17,573	8,893	46,410	22,206
Sales and marketing	96,048	53,454	239,741	130,769
General and administrative	23,806	11,994	63,264	29,591
Total operating expenses	137,427	74,341	349,415	182,566
(Loss) income from operations	(1,679)	(1,063)	2,143	675
Interest income, net	3,231	477	6,753	1,376
Other income, net	978	128	2,921	214
Net income (loss) before provision for income taxes	2,530	(458)	11,817	2,265
Income tax expense	319	140	1,851	378
Net income (loss)	2,211	(598)	9,966	1,887
Undistributed earnings attributable to participating securities	(4)	0	(2,493)	(1,887)
Net income (loss) attributable to common stockholders	$ 2,207	$ (598)	$ 7,473	$ 0
Net income (loss) per share attributable to common stockholders:
Basic (in dollars per share)	$ 0.01	$ (0.01)	$ 0.03	$ (0.00)
Diluted (in dollars per share)	$ 0.01	$ (0.01)	$ 0.03	$ (0.00)
Weighted-average shares used in computing net income (loss) per share attributable to common stockholders:
Basic (in shares)	273,316,850	85,645,323	219,295,445	83,198,339
Diluted (in shares)	292,771,122	111,000,300	241,512,569	109,303,996