Key Detector

An Ableton Live extension that detects the most likely musical key and scale of your MIDI material, available as a Detect Key right-click action throughout Live.

It analyses the notes you point it at, builds a duration-weighted pitch-class histogram, and correlates that against major, minor, and the five common modal families (Dorian, Phrygian, Lydian, Mixolydian, Locrian) at all twelve roots. Results are ranked by correlation and shown in a modal, normalised so the best match reads 100%.

Features

• Detect Key on a MIDI clip — right-click a clip in the Arrangement or Session view. If you have notes selected in the piano roll, only the selection is analysed.
• Detect Key on a Session clip slot.
• Detect Key (All Clips) on a MIDI track header — pools every MIDI clip on the track, across both Session and Arrangement.
• Detect Key on an Arrangement time selection — pools the MIDI clips that overlap the selected time range across the selected tracks.
• Two weighting profiles for the correlation: Krumhansl-Kessler and Temperley.
• Muted notes are ignored so they don't skew the analysis.

Requirements

• Ableton Live 12 (with the Extensions runtime).
• Node.js 22.11.0 or newer (to build).