Chordindex

Play a chord. See the name. Chordindex listens to whatever you're playing — a MIDI keyboard, the on-screen piano, or the on-screen fretboard — and names it in under a second: the name a musician would say in rehearsal, plus two to six alternate names when they apply. Triads, sixths, sevenths, adds, extensions, altered chords, slash chords and inversions — all identified live, spelled for whatever key you're playing in. Every chord shows the same way on three instruments at once: grand staff, piano, and guitar fretboard. Play a shape on the fretboard and see it on the piano; play a chord on your MIDI keyboard and watch the staff and fretboard follow along. It's also a reverse dictionary. Look up a chord by name and see its tones, its common aliases, a piano voicing, a guitar diagram, and the staff — no instrument required. FEATURES • Live identification: triads, sixths, sevenths, adds, extensions, alters, slash chords • Two to six alternate names, ranked for what a musician would actually call it • Grand staff, piano, and fretboard views of the same notes, always in sync • Reverse lookup: search by name, see the voicing • Rootless mode for the voicings your left hand would actually use • Sustain pedal support (CC64), so held chords stay named after you release the keys • Works with USB MIDI, Bluetooth MIDI, and other apps' virtual MIDI output • No MIDI keyboard? The on-screen piano and fretboard work standalone • iPad teaching layout with all three views on screen together; a focused, stacked layout on iPhone • Light and dark themes PRIVACY Chordindex works offline. No account, no analytics, no microphone. MIDI is read only — the app never mutes, routes, or captures your instrument's actual sound. Chordindex is an independent app. It is not affiliated with any other chord product.