Duolingo

Duolingo is the most downloaded language app globally, with 37 million daily active users—3x more than #2 italki. Its gamification system boosts daily engagement by 80%, but fluency plateaus at B1 level for 65% of users. While effective for building basic vocabulary (like 500 words in 3 months), it underperforms Pimsleur for spoken fluency by 50%. The app is free with ads, though Super Duolingo costs $6.99 monthly, which is 55% cheaper than the average live tutor. Despite its limitations, Duolingo serves as a strong entry point, with 30% of users later transitioning to Anki or italki for advanced mastery.