iHarmony is an iOS app that provides a complete collection of all scales, chords and harmonization that you can use for your music.

This app has over 1500 entries and includes a number of audio clips so you can actually here the scales, chords, and harmonization in action. This means you have with you a travelling encyclopedia of scales for instant use whenever and wherever needed.

Very useful when writing music, analyzing jazz standards, doing musical homework, composing a song or even when simply jamming with your friends.