I use the following android apps quite regularly for music-related purposes like finding scales, chords, etc:
* Chord! (the paid version of Chord! Free)
This one is a great, all-around chord and scale program. You can even punch in notes and it will suggest scales for you.
* Chordbot Lite
This one is good pretty much for one thing: selecting chords to be played in a progression, so you can hear how different chord progressions sound.
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