Income taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred tax assets:
Accruals and reserves	$ 4,795	$ 2,540
Deferred revenue	45,268	29,807
Net operating loss	42,008	37,053
Research and development tax credits	13,301	0
Stock-based compensation	2,952	1,487
Indirect tax reserves	4,107	5,682
Property and equipment, net	1,799	1,665
Other	351	299
Gross deferred tax assets	114,581	78,533
Valuation allowance	(97,010)	(69,766)
Total deferred tax assets	17,571	8,757
Deferred tax liabilities:
Deferred contract costs	(10,009)	(5,774)
Other deferred tax liabilities	(7,562)	(3,132)
Total deferred tax liabilities	(17,571)	(8,906)
Net deferred tax liabilities	$ 0	$ (149)