MIDIFLOW: Turn any audio into editable MIDI, 100% in your browser

Hey Product Hunt 👋 Spotify open-sourced Basic Pitch, a genuinely good polyphonic audio-to-MIDI model. But the only ways to use it were installing a Python package (which fights you on newer Python versions) or their demo site, which has been stuck on "Loading file..." for a lot of people for months. So I rebuilt it as a plain static page. The model runs entirely in your browser via TensorFlow.js, which means: • Your audio never leaves your device — there's no upload and no server doing the work • Free, no signup, no watermark, no file limits • You get a standard .mid file that opens in any DAW Hum a melody, drop in a guitar riff, or pull the notes out of an old recording. Being honest about the limits: clean solo instruments and vocals transcribe well. Dense full mixes with drums and heavy reverb are still hard — that's the model, not the page. There's a sensitivity slider so you can tune how aggressive the note detection is, and a piano roll so you can see what it found before downloading. Full credit to the Basic Pitch team at Spotify — it's their model (Apache-2.0), I just wrapped it for the browser. Curious what you try it on 🎹