Circle of Fifths: Notes arranged by musical fifths (C→G→D→A...). Adjacent notes sound harmonically related - great for understanding chord progressions and key relationships.

Chromatic: Notes arranged by semitones (C→C#→D→D#...), matching the linear layout of a piano keyboard.

Accidentals: Toggle how black keys are displayed.

Flats (♭): D♭, E♭, G♭, A♭, B♭ - common in jazz and classical.

Sharps (♯): C♯, D♯, F♯, G♯, A♯ - common in rock and pop.

Sound: Play sine wave tones for pressed notes.

Useful if your MIDI controller doesn't produce sound, or for ear training.