https://techcrunch.com/2018/06/11/memrise-raises-15-5m-as-its-ai-based-language-learning-app-passes-35m-users/

Memrise, a UK startup whose eponymous language-learning app employs machine learning and localised content to adapt to users’ needs as they progress through their lessons, has raised another $15.5 million in funding to expand its product. The funding comes after a period of strong growth: Memrise has now passed 35 million users globally across its 20 language courses, and it tipped into profitability in Q1 of this year. Ed Cooke, who co-founded the app with Ben Whately and Greg Detre, told TechCrunch that this places it as the second-most popular language app globally in terms of both users and revenues.

(Duolingo has more signups, Babbel more revenue.)