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 Portuguese courses, both Brazilian and European. Any 5 minutes of your spare is a good time to learn Portuguese, on any device. Best of all, these courses are entirely free. Read the full review of Memrise.