Fretcetera app for iPhone and iPad

Fretcetera is musical calculator that uses algorithms to connect you to chords, scales and progressions on a variety of string instruments in any tuning!

This is not just a chord book. Fretcetera computes every way to play chords or scales in any tuning, and returns the top results based on their playability. Fine-tune results by configuring your instrument exactly as you play it. Enter personal preferences and constraints. Select from common tunings or create your own!

Build progressions to listen to chord transitions, and even get suggestions based on the chords you are playing!