A free app for Android, by TenguLogi.

If you want to learn Hangul, then this application is for you because this allows you to learn the Korean language effectively and efficiently. This application has different lessons for you to encounter as you progress. It also has reading and writing exercises for you to improve your skills in learning the language.  There are also quizzes and flashcards that will test your skills if you have truly learned the language. Moreover, this application has a seamless flow of learning your modules and for you to easily retain the knowledge you have learned. Most importantly, Hangul Korean Alphabet is totally free.