ChordScope

The ChordScope iOS App visualizes harmony in real time from MIDI input.

Connect a MIDI keyboard or controller and play. ChordScope detects the chord you’re playing and highlights the corresponding notes on a one-octave piano keyboard. 
Notes that belong to the chord’s scale are shown clearly, making harmonic relationships easy to understand at a glance.
Ideal for musicians, composers, and learners, ChordScope provides immediate visual feedback to help you explore chords and progressions as you play.