Revenue - Schedule of total revenue by geographic areas (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2020	Jul. 31, 2019
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 138,281	$ 99,368	$ 268,610	$ 188,756
MongoDB Atlas-related
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	61,074	36,787	115,244	67,650
Other subscription
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	71,404	57,369	142,090	110,500
Services
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	5,803	5,212	11,276	10,606
Americas
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	87,043	64,967	168,581	122,730
Europe, Middle East and Africa
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	40,201	27,810	79,210	53,231
Asia Pacific
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenue	$ 11,037	$ 6,591	$ 20,819	$ 12,795