80 ratings

An open-source, cross platform synthesizer that uses pitch detection to choose candidates for granular synthesis or sampling.

If you're interested, you can view the source and give feedback. If you want to hear the sound demo, scroll to the bottom of this page!


gRainbow was created to overcome a few shortcomings of traditional granular synths.

  1. Pitch variations in the input clip can produce inharmonic tones, which isn't always wanted. This leads users to often use short single-pitch clips, restricting the synth to a single timbre.
  2. Manual pitch matching to the input clip is often required to produce the correct notes with MIDI input, which can be difficult and repetitive.
  3. Pitch shifting is commonly done with timestretching, which can create unwanted artifacts when shifting multiple octaves in either direction.

Instead, gRainbow prefers longer, pitch-diverse audio clips (1), automatically produces harmonics matched for MIDI input (2) and avoids too much timestretching by generating harmonics that are already near their target pitch (3). Voila!


  • Full MIDI range, polyphonic voicing
  • Quick and reliable pitch detection using Spotify's BasicPitch machine learning model
  • Up to 150 grains playing at once
  • Ultra-customizable parameters that can be overriden at the per-note and per-generator level
    • Grain envelope shape, tilt, rate and duration parameters
    • Pitch, pan and grain position spray and adjustment parameters
    • Play grains in forward or reverse
    • Option to sync rate parameters to the host BPM
    • Option to play a reference tone for each note to help dial in pitches
    • and more!
  • Full internal modulation and mapping system
    • Amplitude envelope and 2 additional envelope modulators
    • 3 LFO modulators
    • 4 macros
    • Preset loading and saving system that bundles the audio sample into the preset for you - Cute clouds that sing!

For more details, check out the official project page. Join our Discord server to chat and get more frequent product updates!

Here's a sound demo of the product's presets:

I want this!

You'll get a package for your platform (Windows, MacOS or Linux) of a standalone and plugin version (VST, AU, LV2) of gRainbow and a 10 preset starter pack. Make it grain!


(80 ratings)
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80 ratings
I want this!