Share-based compensation - Stock-based compensation expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 35,805	$ 6,743	$ 2,461
Cost of revenue: | Services
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	594	139	0
Cost of revenue: | Subscription
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	3,755	732	194
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	10,938	1,748	460
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	10,512	1,533	394
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based compensation expense	$ 10,006	$ 2,591	$ 1,413