CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) $ in Thousands		12 Months Ended
		Jan. 31, 2019	Jan. 31, 2018		Jan. 31, 2017
Revenue:
Revenues		$ 267,016	$ 166,028	[1]	$ 114,805	[1]
Cost of revenue:
Total cost of revenue		73,568	42,859	[1]	29,867	[1]
Gross profit		193,448	123,169	[1]	84,938	[1]
Operating expenses:
Sales and marketing		148,296	109,073	[1]	75,413	[1]
Research and development		89,854	62,202	[1]	51,772	[1]
General and administrative		53,063	36,775	[1]	27,082	[1]
Total operating expenses		291,213	208,050	[1]	154,267	[1]
Loss from operations		(97,765)	(84,881)	[1]	(69,329)	[1]
Other income (expense):
Interest income		7,163	1,308	[1]	302	[1]
Interest expense		(10,290)	(8)	[1]	(9)	[1]
Other income (expense), net		(1,437)	895	[1]	(308)	[1]
Loss before provision for (benefit from) income taxes		(102,329)	(82,686)	[1]	(69,344)	[1]
Provision for (benefit from) income taxes		(3,318)	1,287	[1]	719	[1]
Net loss	[2]	$ (99,011)	$ (83,973)	[3],[4]	$ (70,063)	[3],[4]
Net loss per share attributable to common stockholders, basic and diluted - (in dollars per share)		$ (1.90)	$ (3.54)	[1]	$ (5.74)	[1]
Weighted-average shares used to compute net loss per share attributable to common stockholders, basic and diluted for Class A and Class B (in shares)		52,034,596	23,718,391	[1]	12,211,711	[1]
Subscription
Revenue:
Revenues		$ 248,391	$ 151,853	[1]	$ 104,033	[1]
Cost of revenue:
Total cost of revenue		56,255	30,766	[1]	19,352	[1]
Services
Revenue:
Revenues		18,625	14,175	[1]	10,772	[1]
Cost of revenue:
Total cost of revenue		$ 17,313	$ 12,093	[1]	$ 10,515	[1]

[1] See Note 2 for a summary of adjustments.

[2] See Note 2 for a summary of adjustments.

[3] See Note 2 for a summary of adjustments.

[4] See Note 2 for a summary of adjustments.