XML 11 R1.htm IDEA: XBRL DOCUMENT v3.21.2
Cover Page - shares
 6 Months Ended
Jun. 30, 2021
Aug. 11, 2021
Document Information [Line Items]    
Document Type 10-Q  
Document Quarterly Report true  
Document Period End Date Jun. 30, 2021  
Document Transition Report false  
Entity File Number 001-40653  
Entity Registrant Name Duolingo, Inc.  
Entity Incorporation, State or Country Code DE  
Entity Tax Identification Number 45-3055872  
Entity Address, Address Line One 5900 Penn Avenue  
Entity Address, City or Town Pittsburgh  
Entity Address, State or Province PA  
Entity Address, Postal Zip Code 15206  
City Area Code 412  
Local Phone Number 567-6602  
Title of 12(b) Security Class A common stock, $0.0001 per share  
Trading Symbol DUOL  
Security Exchange Name NASDAQ  
Entity Current Reporting Status No  
Entity Interactive Data Current Yes  
Entity Filer Category Non-accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company true  
Entity Shell Company false  
Entity Ex Transition Period false  
Entity Central Index Key 0001562088  
Current Fiscal Year End Date --12-31  
Document Fiscal Year Focus 2021  
Document Fiscal Period Focus Q2  
Amendment Flag false  
Common Class A    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   12,819,870
Common Class B    
Document Information [Line Items]    
Entity Common Stock, Shares Outstanding   24,598,497