I am a language learning nerd, and I have been down the rabbit hole. Let me tell you that the most popular tool for serious language learners is Anki because of

I am a language learning nerd, and I have been down the rabbit hole. Let me tell you that the most popular tool for serious language learners is Anki because of the spaced repetition. If you pursue a startup in the space, I highly recommend incoporating spaced repetition. Another question to ponder: Who is the audience and what value will they get from learning a language. For example, the audience could be people immigrating to America for college. That is a group of people who have a strong need to learn English.