Piano Companion is a piano chords and scales dictionary with user libraries and reverse mode with a chord progression builder. Our free app has circle of fifths with compatible chords (or chord wheel). Using circle of fifths and chord progression builder you can compose songs and learn, play chords and scales. You can compose music using our real piano and use your MIDI keyboard to play and record songs. It helps you to learn music theory too. If you can’t remember the name of a chord or scale,