REVENUE - Schedule of Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 1,037,589	$ 748,024	$ 531,109
Subscription
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	873,442	607,531	404,684
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	164,147	140,493	126,425
Advertising
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	79,725	54,907	49,858
Duolingo English Test
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	42,006	45,640	41,212
IAPs
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	40,479	38,653	34,673
Other
Disaggregation of Revenue [Line Items]
Revenue from contract with customer, excluding assessed tax	$ 1,937	$ 1,293	$ 682