Each mistake made will cost you one heart, and for each practice lesson you complete, you’re rewarded with a new heart. In addition to the app’s free tier, Duolingo has multiple paid ...
Language-learning app Duolingo makes around $500 million annually, despite offering all of its lessons for free. WSJ explores how the company is using AI and A/B testing to keep users hooked.
Some results have been hidden because they may be inaccessible to you
Show inaccessible results
Feedback