Pymss

B tier on AI Stem SplittersScore 7.4 · #2 of 26

Android app: Yes
Free plan: Yes
Runs on: Android, api, iOS, Linux, Mac, Web, Windows

pymss.net

Summary

Pymss is a free, open-source music source separation toolchain that runs on the user's own machine and separates audio into vocals, drums, bass, and other stems. Its Studio desktop workspace supports model management, batch jobs, and stem editing. Users can import files or folders, choose a downloaded model, configure inference, and queue processing jobs. Studio also provides model browsing and downloads, resume and delete controls, and storage cleanup. For working with results, it includes waveform previews, mix controls, saved projects, and stem export. Pymss can chain models so that each step processes the preceding step's output. Listed output formats are WAV, FLAC, MP3, M4A, AAC, Opus, Vorbis, and Ogg. The project also provides ComfyUI custom nodes, a VST3 ARA plugin for compatible DAWs, and a browser interface bundled with its server. The ARA plugin offers per-stem mute and solo controls; its README names Reaper and Studio One as example hosts. Each repository has its own license; the Studio listing is AGPL-3.0 and the inference package MIT. Studio is at an early development stage, and breaking changes may occur between versions.

Who it is for

Pymss suits people who want to separate music into stems locally, including users who need batch processing or editing tools. Its ARA plugin and ComfyUI nodes also suit people working with compatible DAWs or ComfyUI.

What is good

Runs separation on the user's own machine
Studio supports batch jobs and stem editing
Can chain models into processing workflows
Lists eight supported output formats
Free and open source

What to know first

Studio is at an early development stage
Breaking changes may occur between versions

Verdict

Pymss brings local separation, batch processing, model management, and stem editing into one toolchain. Its early Studio development status is worth considering if you depend on stable behavior between versions.

Pymss plans and pricing

All plans

Pymss Free Free · open source · runs locally pymss.net · 30 Sept 2026

Compared on AI stem splitters

Free plan: Yespymss.net
Batch processing: Yespymss.net
Export formats: WAV, FLAC, MP3, M4A, AAC, Opus, Vorbis, OGGpymss.net
API access: Yespymss.net

Facts

Purpose: Pymss is an open source music source separation toolchain that separates vocals, drums, bass, and other stems on the user's machine.pymss.net · 30 Sept 2026
Studio: Pymss Studio is a desktop workspace for model management, batch jobs, and stem editing.github.com · 30 Sept 2026
Import and batch: Studio can import audio files or folders, select a downloaded model, configure inference, and queue jobs.github.com · 30 Sept 2026
Model library: Studio can browse, download, resume, and delete model files, and manage storage cleanup.github.com · 30 Sept 2026
Editing and export: Studio provides waveform preview, mix controls, project persistence, and stem export.github.com · 30 Sept 2026
Workflows: Pymss can chain models into processing workflows, with each step using the previous step's output.pymss.net · 30 Sept 2026
Formats: The inference package lists WAV, FLAC, MP3, M4A, AAC, Opus, Vorbis, and Ogg as supported output formats.github.com · 30 Sept 2026
Integrations: The project provides ComfyUI custom nodes and a VST3 ARA plugin for use in DAWs.pymss.net · 30 Sept 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 · 30 Sept 2026
Platforms: The official site lists Windows, macOS, and Linux for Studio and CLI, iOS and Android for the mobile runtime, and Windows for the ARA plugin.pymss.net · 30 Sept 2026
Browser interface: The WebUI is described as a browser interface bundled with the server and shipped with the pip package.pymss.net · 30 Sept 2026
Local processing: The official site says separation runs entirely on the user's own machine.pymss.net · 30 Sept 2026
Licensing: The official site says each repository ships under its own license; GitHub lists Studio under AGPL-3.0 and the inference package under MIT.github.com · 30 Sept 2026
Support: The project points users to GitHub documentation and an issue tracker, and its Studio README lists a QQ group for Chinese beta testing, bug reports, and community discussion.pymss.net · 30 Sept 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 · 30 Sept 2026