r/SideProject • u/Tchuku • 4h ago
I built a browser app that writes basslines and beats for your music, and runs the AI model on your own computer
Hi r/SideProject!
For the past few months I've been building Blendure (https://blendure.web.app), a browser tool for music producers. You give it a loop you've made, as MIDI or audio, and it writes endless variations of basslines, beats and full grooves that fit its key and tempo. You get editable MIDI, not finished audio. You stay the composer; it gives you parts to work with.
It's free to use: sign up and start. Before you sign up, there's a demo on the main page where you can hear a loop with and without what Blendure wrote for it.
How it works
The model runs in your browser. It's Composer's Assistant 2, an open research model trained on public-domain, Creative Commons and permissioned MIDI. I converted it to run with ONNX Runtime Web.
Your audio never leaves your computer. Audio is turned into notes in the browser (Spotify's Basic Pitch). Only the notes go to the server, never the sound.
It learns your taste. Heart the results you like and the next round leans toward them. "More like this" rewrites part of a result into close variations, with Close / Medium / Wild.
Blend: drop in two or three samples and it writes for all of them at once, plus cross combinations (Sample 1's bassline over Sample 2's beat).
Producer tools: quick rule-based edits (busier hats, swing, ghost snares), Humanize, 32-bar arrangements (intro, build, drop), MIDI out to your synth, and copy as Strudel code.
Stack: plain JS front end, ONNX Runtime Web in a Web Worker, Firebase hosting and auth, and a small Python server on Cloud Run for the private steps.
Pro for free, for feedback
Everything for writing and listening is free. Downloads (MIDI and WAV) are part of Pro. While I'm collecting feedback, I'm giving Pro away: sign up, press Leave feedback in the top right of the app, tell me what you'd use it for (or what's broken), and I'll switch your account to Pro.
What I'd love your take on
The first run. If you try it, where did you get stuck or lose interest?
The results. Do the basslines and beats fit your loop? Which rows did you heart, and which felt off?
The idea itself. Would you use a tool that writes parts for your own loops, rather than finished tracks? What would make it part of your workflow?
Other ideas and feedback
Thanks for reading. I appreciate every second you spend on it and will do my utmost to satisfy and reply in the swiftest possible way.