Malsah Labs has released HarmonyKeen, an app and plugin that is designed to write harmony parts around a melody you give it as MIDI.
HarmonyKeen reads the whole melody before it writes anything: it finds the phrases and the cadences, picks a chord sequence that fits, and then writes the added voices by the rules of voice leading. There’s no neural network in it. The engine is built on music theory, so the same melody with the same settings gives the same result every time.
Features:
- Melody in as a MIDI file, drawn on the piano roll, played from a keyboard, or captured from a track in the DAW (plugin).
- Styles from a single companion line, through close vocal harmony and four-part writing, to fuller arrangements.
- One to three added voices, placed above the melody, below it, or both.
- Every generated note can be edited.
- Output to the DAW as MIDI, one part per track, or as sheet music with PDF and MusicXML export for MuseScore, Dorico, Sibelius and Finale.
- Automatic key detection, with a manual override.
- Standalone app on macOS and Windows; VST3 on both; Audio Unit on macOS, including a separate version for GarageBand.
- Hosts include Logic Pro, GarageBand, Ableton Live, Cubase, FL Studio and Reaper.
Pricing & Availability
HarmonyKeen is available now at an introductory price of $59. It stays at $59 until version 1.1, the next major engine update, and at least through October 15, 2026.
It runs on macOS 11 or later on Apple Silicon, and on 64-bit Windows 10 version 2004 or later, or Windows 11.
Audio demos, no signup: harmonykeen.com/hear-it
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