Short pieces of music composed from a description of a mood.
Describe a mood or a scene and get a loop with chords, melody, bass and drums, played by a synthesizer in your browser. Change the tempo, sounds and mix, program your own drums, and export MIDI or WAV.
The app itself, running inside this page. Anything you do here is saved in your browser.
Ask it to do things
Press Ctrl+K in the app (Cmd+K on a Mac) and describe what you want. The model chooses from the app's own functions, runs them in order and tells you what changed. Some examples:
| Rainy café at midnight, slow and jazzy | Composes a new piece for that mood and plays it. |
| Slower, and swap the lead for something softer | Changes the tempo and lead sound. |
| Save this to my library | Stores the piece with its mood. |
Instructions you save in the same box, such as "keep it short" or "I'm a beginner", are added to every AI request the app makes.
Features
- AI composition as JSON
- Key, mode, tempo, 8-chord progression, 32-beat melody, drum style, timbres.
- Chord-symbol parser
- Maj7, m7b5, sus, add9, slash chords …) and scale/chord-tone quantizer.
- Algorithmic composer fallback
- Roman-numeral progressions per mode, chord-tone-anchored random-walk melodies.
- Web Audio synth
- ADSR voices, lowpass filtering, synthesized kick/snare/hats, generated reverb impulse, compressor.
- Lookahead scheduler
- Chris Wilson pattern) with humanized timing and velocity.
- Canvas piano roll
- With live playhead and chord highlighting.
- Tempo
- Transpose, timbre, drums, reverb controls; AI variations; Standard MIDI File export (4 tracks).
- Library page
- Save pieces with their mood, rename inline, pin favorites, sort by newest / most played / tempo, mini piano-roll previews, JSON export and import.
- Chord lab page
- Type any progression for Krumhansl–Schmuckler key detection with ranked candidates, roman-numeral analysis with harmonic function, cadence detection and borrowed-chord highlighting.
- Reharmonization
- Tritone substitutions, relative major/minor, secondary dominants and modal borrowing, plus AI reharmonization options; send a progression to the composer.
Runs in your browser
Music theory, quantization, synthesis, scheduling, visualization, MIDI writing. None of this needs a network connection or a model.
Uses a language model for
Mood → full structured composition. Variation mode: rewrites the melody as call-and-response while keeping the harmony.
Notes
- Cost
- Free. Each account has a daily allowance of AI requests.
- Your data
- What you make stays in this browser on this device. Your account is only used for signing in and for the built-in AI. You can export a backup or clear everything from Settings.
- AI access
- Signed-in users get the built-in AI with nothing to set up. You can also use your own Groq or OpenRouter key under Settings.
- Source
- The code and tests are on GitHub under the MIT license. The tests also run in your browser.