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Pymss
What it is
Pymss is a free, open-source music source separation toolchain that processes audio on the user’s machine, separating vocals, drums, bass, and other stems. Its desktop workspace, Pymss Studio, handles model management, batch processing, and stem editing. Import audio files or folders, choose a downloaded model, configure inference, and queue jobs. Studio can also browse and manage model files, including resuming downloads, deleting files, and cleaning up storage. For results, it provides waveform previews, mix controls, saved projects, and stem export. Workflows can chain models so each step receives the output of the prior step. Listed output formats include WAV, FLAC, MP3, M4A, AAC, Opus, Vorbis, and Ogg. The project also offers a browser interface, ComfyUI custom nodes, and a VST3 ARA plugin with per-stem mute and solo controls for compatible DAWs. It is available on Android, iOS, Linux, macOS, web, and Windows, with API access. Studio is at an early development stage, and breaking changes may occur between versions.
For and against
For
- Runs separation on the user's own machine
- Studio supports batch jobs and stem editing
- Chains models into multi-step workflows
- Lists eight output audio formats
- Free and open source
Against
- Studio is in early development
- Breaking changes may occur between versions
- Each repository uses its own license
The verdict
Pymss combines local stem separation with batch processing, editing, and model chaining. Its early development status and repository-specific licensing are worth noting before adopting it.
Who it suits
Pymss suits people who want to separate audio into stems locally, including users who need batch jobs or editing controls. Its integrations may also suit users of ComfyUI or ARA-capable DAWs.
Plans and prices
Pymss
Free · open source · runs locally
Read 30 Sep 2026 · pymss.net
On the record
- ARA integration
- The ARA VST3 plugin separates DAW tracks into stems in a background worker and supports per-stem mute and solo monitoring.github.com · read 14 Oct 2026
- ARA plugin
- The ARA plugin separates tracks inside an ARA-capable DAW and provides per-stem mute and solo controls; its README names Reaper and Studio One as example hosts.github.com · read 30 Sep 2026
- Audio utilities
- Included tools cover conversion, inspection, SDR and SI-SDR evaluation, speech recognition, vocal-to-MIDI, silence slicing and audio merging.github.com · read 14 Oct 2026
- Browser interface
- The WebUI is described as a browser interface bundled with the server and shipped with the pip package.pymss.net · read 30 Sep 2026
- CLI
- The command line supports inference, workflows, ComfyUI JSON execution, ensembles, model registration and server startup.github.com · read 14 Oct 2026
- ComfyUI integration
- Comfy-MSS provides nodes for catalog, custom-model and VR/UVR separation inside ComfyUI.github.com · read 14 Oct 2026
- Custom models
- Users can import weights and configurations for supported model architectures.github.com · read 14 Oct 2026
- Development status
- The Studio README says the app is at an early stage of feature development and breaking changes may occur between versions.github.com · read 30 Sep 2026
- Editing and export
- Studio provides waveform preview, mix controls, project persistence, and stem export.github.com · read 30 Sep 2026
- External usage
- The RVC project describes its PyMSS integration as providing model cataloging, downloading, audio I/O and ensemble utilities.codeassuranceindex.info · read 14 Oct 2026
- Formats
- The inference package lists WAV, FLAC, MP3, M4A, AAC, Opus, Vorbis, and Ogg as supported output formats.github.com · read 30 Sep 2026
- HTTP API
- The optional server extra provides a self-hostable HTTP service with dynamic model loading, catalog browsing, downloads and an optional WebUI.github.com · read 14 Oct 2026
- Import and batch
- Studio can import audio files or folders, select a downloaded model, configure inference, and queue jobs.github.com · read 30 Sep 2026
- Integrations
- The project provides ComfyUI custom nodes and a VST3 ARA plugin for use in DAWs.pymss.net · read 30 Sep 2026
- Licensing
- The main Python package is MIT licensed according to PyPI.pypi.org · read 14 Oct 2026
- Limit: Intel Mac
- There is no dedicated Intel Mac package; source builds require checking inference dependency compatibility.github.com · read 14 Oct 2026
- Limit: Linux packaging
- The current release workflow does not provide Linux installers.github.com · read 14 Oct 2026
- Limit: mobile
- iOS and Android GPU or NPU support is described as future research, with no mobile application release currently provided.github.com · read 14 Oct 2026
