Foss

Foss 1.0.0 is a Mac app that takes any track and splits it into four clean stems — vocals, drums, bass, and everything else — as lossless FLAC files. While it separates, it also works out the track's key (with the Camelot code) and BPM, and writes it all into a tidy little report next to your stems.

Everything runs on your own Mac. Nothing is uploaded, no account, no subscription inside the app, no internet needed after download. The AI models that do the separation (the same BS-Roformer + Demucs combination you'd normally have to wrangle on the command line) are already inside the app — there's nothing to install or configure.

How to use it:

1. Unzip the download and drag Foss into your Applications folder.
2. Open it, and drop an audio file (.mp3, .flac, or .wav) onto the window — or click to browse.
3. Press Process queue. A typical track takes around 8 minutes on an Apple Silicon Mac (Foss uses the Mac's GPU automatically).
4. When it's done, your track shows up in the Library — one folder per track with the four stems, your original file, and the key/BPM report. "Reveal in Finder" takes you straight there, ready to drag into your DAW or DJ software.

Tip: flip on Watch folder and Foss will automatically process anything you drop into its ingest folder while it's running — queue up a whole crate and walk away.

Requirements:

• Apple Silicon Mac (M1 or newer).
• macOS 13 Ventura or newer.
• ~2 GB of free disk space for the app.

The fine print:

Foss includes FFmpeg (ffmpeg.org), the FFmpeg developers, licensed under LGPL v2.1+. Build details and the license are included inside the app.

Found a bug or got a track that trips it up, or just general questions? Let me know on Patreon — failed files stay put so you can always just hit Retry after an update.

Built by OlavK — more tools and updates at patreon.com/OlavK.