Memrise courses are usually fun. Most of them are generated by users, and the quality varies, but when you pick one, learning the lessons is like playing a game. The concept of the app will make you memorize words, phrases, spelling, pronunciation, syntax, just name it. And you can choose from hundreds of courses or create your own. Any 5 minutes of your spare is a good time to learn Hindi, on any device. Best of all, these courses are entirely free. Read the full review of Memrise.