During the Super Bowl on Sunday, the language learning company spent a crazy amount of money on a five-second ad featuring Duolingo’s new booty. The clip featured Duo’s BBL expanding and then ...

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.

Learn more about my experiences with Duolingo, Babbel and Pimsleur below, including the sign-up process and lesson structure for each one. SKIP AHEAD Get to know the apps | How I tested the ...