Progress your chord progressions with Chorder. Chorder gives you the ability to develop chord progressions in any key and a variety of voicings (modes). You can even give your chord progressions structure to create songs or structured outlines for your composition.
Chorder lets you know when a chord doesn't fit the key and mode you've selected by highlighting the notes that aren't in that scale. This gives you a clear idea of which chords will fit your progression before you select anything.