v3.22.0.1
REVENUE - Disaggregation of Revenue (Details) - USD ($)
$ in Thousands
 12 Months Ended
Dec. 31, 2021
Dec. 31, 2020
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax $ 250,772 $ 161,696
Subscription    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax 180,698 117,501
Advertising    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax 38,501 27,043
Duolingo English Test    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax 24,658 15,155
Other    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax 6,915 1,997
Over time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax 180,698 117,501
Point in time    
Disaggregation of Revenue [Line Items]    
Revenue from contract with customer, excluding assessed tax $ 70,074 $ 44,195