A free app for Android, by BrainSides.

This is an application developed by Brazilian musicians, to help musicians, both beginners and advanced, in learning to play the acoustic or electric guitar, by providing them with a large and varied database of chords and scales. It is the most complete and best application of its kind.

The application was created to help you learn to play the guitar with thousand of chords. The first thing you will learn is how to read chords and scales. It is an illustrated dictionary, with thousands of examples, that are all displayed with a picture, so you can have the best view.