stemdeckapp/stemdeck

Stemdeck is an modern stem extraction platform for musicians,producers and hobbyists, designed to isolate vocals, drums, bass, piano and guitar for practice, transcription, remixing, and creative ...

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README

Free, local stem separation. No account. No upload. No subscription.

JOIN THE COMMUNITY

Drop in an MP3, WAV, FLAC, OGG/Opus, MP4, or M4A file, or paste a YouTube URL, and StemDeck splits the audio into up to six stems (vocals, drums, bass, guitar, piano, other). Play them back in a DAW-style multitrack mixer: mute, solo, balance levels, zoom the waveform, loop a region, and export individual stems or a custom mix. Everything runs locally on your own machine.

What is this? StemDeck is a stem separation tool, not a downloader. Its main job is processing audio you already own: drag an MP3, WAV, FLAC, OGG, or M4A onto the import bar and go. YouTube support is a convenience for content you have the right to process. StemDeck does not store, cache, or redistribute any downloaded content. Everything happens locally and nothing leaves your machine.

StemDeck is a free, open alternative to cloud stem-splitters like Moises and LALAL.AI: no account, no quota, no uploads, no subscription. If you want stems for personal study and prefer to keep things local and free, StemDeck has you covered. If you need the polish, a mobile app, or deeper musician tooling, the commercial products are a better fit.

We Recommend StemDeck is free and does not accept any money, sponsorship, or funding - not from users, not from anyone listed below. We share these makers and artists purely for the joy of pointing you toward wonderful people doing beautiful work. Go meet them ❤️

Name What they do Link

Dlima Guitars Custom guitars and basses @dlimaguitars

Lisbon Guitar Works Guitar building dlimaguitars.com

Joao Gaspar Producer/Film Scorer, Touring/Session Musician @jay_glaspar

Kris Luthier Luthier and Musical Instrument Repair, Lisboa @krisluthier

Thomann Online Music Store @thomann.music

Analog4Lyfe Analog music gear @analog4lyfe

Empress Effects Effects pedals empresseffects.com

More Notes Less Talk Instruments and gear with personality, recorded raw to tape. No hype, no gatekeeping. @morenoteslesstalk

Features 6-stem separation via Demucs htdemucs_6s, with auto-detection of the best Torch device (CUDA on NVIDIA, MPS on Apple Silicon, CPU fallback). YouTube and local file import. Paste a YouTube URL or drop an MP3, WAV, FLAC, OGG/Opus, MP4, or M4A directly onto the import bar. DAW-style waveform editor with min/max sample rendering across all stems, shared normalization, zoom in/out/Fit, loop drag on the ruler, gold playhead overlay, and stem-aligned lanes. Stem subset extraction. Click stem chips to choose which stems to keep. Clicking from "all selected" snaps to "only this one"; subsequent clicks add or remove. "Original" backing track. When you pick a subset, a 7th lane contains the complement (full song minus selected stems), perfect for A/B reference without doubling. Downloadable selected mix. A single mix.wav of just your selected stems, summed via ffmpeg amix. Per-stem mixer with volume fader, mute, solo, and "monitor" (solo-only) per stem. State syncs between the preview mixer and the stems sidebar. Live VU meters per stem. Post-gain RMS via Web Audio analysers with peak hold and slow falloff. Song analysis including BPM (librosa beat tracker), key, scale, and confidence (Albrecht-Shanahan profiles), integrated LUFS (BS.1770), and sample peak in dBFS. Cancellable jobs. Cancel mid-pipeline and the runner terminates the active subprocess immediately, deletes the partial job dir, and returns to ready. Library panel with folder-based track organisation, drag-and-drop, search, and trash.

Honest Comparison StemDeck is not trying to compete with commercial stem-separation products. It covers the core use case well and stops there. This table exists so you can make an informed choice rather than discover the gaps after the fact.

StemDeck Moises / LALAL.AI / similar

Price Free, forever Freemium; credits or subscription required for regular use

Hosting Runs entirely on your machine Cloud; audio must be uploaded to their servers

Account / login None Required

Internet required Only for YouTube download and first model fetch (~170 MB, cached after) Always; no offline use

Privacy Audio never leaves your machine Audio is uploaded and processed on third-party servers

Data retention You control it; delete anytime Governed by their privacy policy and retention period

Stem model Demucs htdemucs_6s (open source, Meta AI) Proprietary models, regularly updated, generally higher quality

Stem count 6 (vocals, drums, bass, guitar, piano, other) Up to 10 depending on service and plan

Input formats YouTube URL, MP3, WAV, FLAC, OGG/Opus, MP4, M4A MP3, WAV, FLAC, M4A, and more depending on service

Processing speed Depends on your hardware; fast with a GPU, slow on CPU only Fast regardless of your hardware (runs on their servers)

Batch processing One job at a time Yes, on paid plans

Mobile app No iOS and Android

Extra features No (no pitch shift, chord detection, lyrics, click track, BPM tap) Yes, varies by product

Polish Functional, hobby-grade UI Polished, production-grade apps

Source code Open source, forkable, self-hostable Closed source

If you need speed, quality, mobile access, or the extra musician tooling, the commercial products are worth the money. If you want stems for personal study, prefer to keep audio private, or just want something that runs locally with no strings attached, StemDeck is enough.

Download Pre-built installers and zips are attached to each GitHub Release. macOS

DMG GPU Chip

StemDeck-macOS-arm64.dmg Apple Silicon (MPS) M1 and later

StemDeck-macOS-x64.dmg CPU only Intel

Open the DMG, drag StemDeck to Applications, and launch it. On first launch the setup screen downloads the Python runtime (~500 MB), FFmpeg, and the Demucs model (~170 MB). Subsequent launches skip setup and start in seconds. No Python or system dependencies required. macOS may show a Gatekeeper prompt on first open — right-click the app and choose Open to bypass it. Windows

Zip GPU Approx. size

StemDeck-Windows-x64.zip CPU only ~700 MB

StemDeck-Windows-x64.NVIDIA.zip NVIDIA CUDA ~1.6 GB

Extract the zip anywhere, run StemDeck.exe. On first launch the app verifies the bundled Python runtime and downloads FFmpeg and the Demucs model (~170 MB). Subsequent launches skip this and start in seconds. Everything is self-contained; no Python or system dependencies required.

Technologies

StemDeck is built on Python 3.12 managed via uv, with a FastAPI backend serving REST and Server-Sent Events. Stem separation uses Demucs (htdemucs_6s), Meta AI's open-source 6-stem neural network. YouTube audio is fetched via yt-dlp; transcoding and mixing use FFmpeg. BPM detection and key analysis run on librosa; loudness measurement uses pyloudnorm (ITU-R BS.1770). The macOS and Windows desktop shells are Tauri v2 (Rust/WKWebView on macOS, Rust/WebView2 on Windows). The frontend is vanilla JS with the Web Audio API, no framework and no build step; waveforms are rendered on <canvas> using min/max sample rendering. Thanks to the creators and maintainers of all the open-source libraries that make StemDeck possible.

Build from Source macOS Native App Requires Rust, Node.js, and Python 3.12. Builds a self-contained .app that downloads its own runtime on first launch.

First time only — add the cross-compilation targets

Build Apple Silicon

Build Intel (requires Rosetta 2 and an x86_64 Python)

Note: To test a clean first-launch during development, you can wipe previous app data first: rm -rf ~/Library/Application\ Support/StemDeck. Don't do this on a real install.

Web Server (macOS / Linux / Windows with Python 3.12+) Prerequisites Python 3.12 or newer, ffmpeg on your PATH, and uv. Around 170 MB of free disk for the Demucs model, which downloads automatically on first run. macOS / Linux (one-shot) git clone https://github.com/stemdeckapp/stemdeck stemdeck && cd stemdeck ./run.sh setup # installs ffmpeg + uv, runs uv sync ./run.sh start Open http://localhost:8000. setup uses Homebrew on macOS and apt-get on Debian/Ubuntu. For other Linux distros, install ffmpeg and uv manually, then run uv sync followed by ./run.sh start. Windows (PowerShell) Install prerequisites:

uv — winget install astral-sh.uv ffmpeg — winget install Gyan.FFmpeg (or Chocolatey: choco install ffmpeg)

git clone https://github.com/stemdeckapp/stemdeck stemdeck; cd stemdeck uv sync uv run uvicorn app.main:app --host 127.0.0.1 --port 8000 --timeout-graceful-shutdown 5 Open http://localhost:8000.

run.sh is macOS/Linux only. On Windows use the PowerShell commands above, or run inside WSL.

NVIDIA GPU (CUDA): install the CUDA-enabled torch build before starting: uv pip install torch torchvision torchaudio --index-url https://download.pytorch.org/whl/cu124 $env:STEMDECK_DEMUCS_DEVICE = "cuda" uv run uvicorn app.main:app --host 127.0.0.1 --port 8000 --timeout-graceful-shutdown 5

Manual (any platform) git clone https://github.com/stemdeckapp/stemdeck stemdeck && cd stemdeck uv sync uv run uvicorn app.main:app --reload --timeout-graceful-shutdown 5

--timeout-graceful-shutdown bounds how long uvicorn waits for open connections when you stop it. StemDeck keeps a long-lived SSE stream open for the import queue while a browser tab is on the app, so without it Ctrl-C waits for that stream instead of exiting.

Docker docker compose -f build/docker-compose.yml up --build Stems land in ./jobs/ on the host. Demucs weights are cached in a named volume so they don't re-download on rebuild. Note: no GPU passthrough on macOS Docker. A prebuilt image is published to GHCR. Tags: edge (rolling, rebuilt on every merge to main), latest (newest stable release), and X.Y.Z (pinned to a release). docker run -d --name stemdeck -p 8000:8000 \ -v /path/to/jobs:/app/jobs \ -v /path/to/cache:/cache \ -e STEMDECK_PERSIST_LIBRARY=1 \ ghcr.io/stemdeckapp/stemdeck:edge On a Linux host with an NVIDIA GPU (driver + NVIDIA Container Toolkit installed), add --runtime=nvidia -e NVIDIA_VISIBLE_DEVICES=all and StemDeck auto-detects CUDA. The image already bundles CUDA-enabled torch, so no separate CUDA install is needed. Unraid StemDeck is available in Unraid Community Applications: open Apps, search "StemDeck", and install. Map the two volumes to persistent appdata paths:

/app/jobs -> /mnt/user/appdata/stemdeck/jobs (library + stems) /cache -> /mnt/user/appdata/stemdeck/cache (model weights)

The library is persistent by default (STEMDECK_PERSIST_LIBRARY=1), so tracks are never auto-deleted. For GPU acceleration, install the Nvidia Driver plugin, then set the container's Extra Parameters to --runtime=nvidia (the NVIDIA_VISIBLE_DEVICES and NVIDIA_DRIVER_CAPABILITIES variables are already in the template). CPU-only works with no extra configuration. run.sh control script ./run.sh setup # one-shot: install ffmpeg + uv, then uv sync ./run.sh start # boots uvicorn in the background ./run.sh stop # graceful shutdown ./run.sh restart # stop + start ./run.sh status # is it running?

How to Use

On the import bar, click stem chips to choose which stems to extract (defaults to all 6). Paste a YouTube URL or drop an audio file (MP3, WAV, FLAC, OGG, MP4, M4A), then click Process. Wait through Uploading... / Downloading... → Analyzing... → Separating... → Mixing tracks.... When done, the studio dashboard appears. If you picked a subset, the first lane is Original (full song minus your selection); the rest are your isolated stems. Mix: Play/Pause/Stop controls the master transport. M mutes a stem, S solos it (additive; multiple solos stay audible), Monitor solos only that stem and clears others. The volume fader moves 1:1 with drag; double-click resets to 0 dB; Shift+wheel gives coarse adjustment and plain wheel gives fine. The Reset, Mute, and Solo toolbar buttons act on all stems at once. Drag on the ruler to define a loop region; click Loop to enable. Use + / - / Fit or Ctrl/Cmd+wheel to zoom. Download Mix in the footer gives you a WAV of your selected stems summed together.

Keyboard shortcuts: Space play/pause · [ seek -5s · ] seek +5s · L loop · I loop in · O loop out

Configuration

Variable Default Purpose

STEMDECK_DEMUCS_DEVICE auto Force Torch device: cuda, mps, or cpu.

STEMDECK_DEMUCS_MODEL htdemucs_6s Demucs model name.

STEMDECK_JOBS_DIR ./jobs Where job directories land.

STEMDECK_DATA_DIR (none) Portable mode root; sets all sub-dirs below to live inside it.

STEMDECK_CACHE_DIR <data>/cache Torch model cache directory.

STEMDECK_DOWNLOADS_DIR <data>/downloads yt-dlp download scratch space.

STEMDECK_MODELS_DIR <data>/models Demucs model weights directory.

STEMDECK_LOGS_DIR <data>/logs Log file output directory.

STEMDECK_FFMPEG_DIR (none) Directory containing a bundled ffmpeg binary.

STEMDECK_FFMPEG ffmpeg Path to the ffmpeg executable.

STEMDECK_FFPROBE ffprobe Path to the ffprobe executable.

STEMDECK_MAX_DURATION_SEC 1200 Reject audio longer than this (seconds).

STEMDECK_JOB_TTL_SECONDS 86400 How long to keep job dirs on disk.

STEMDECK_MAX_PENDING_JOBS 3 Max queued jobs before returning 503.

STEMDECK_TIMEOUT_FFMPEG 300 ffmpeg subprocess timeout (seconds).

STEMDECK_TIMEOUT_ANALYZE 120 Audio analysis timeout (seconds).

STEMDECK_TIMEOUT_DEMUCS_STALL 1800 Kill Demucs if no output for this many seconds.

run.sh also reads: HOST (default 127.0.0.1), PORT (default 8765), RELOAD=1 (enable uvicorn auto-reload for development), FOREGROUND=1 (run in foreground instead of backgrounding).

API

Method Path Purpose

GET /api/health Server health and version info

POST /api/jobs JSON {url, stems?} or multipart file + stems → {job_id}

GET /api/jobs List completed (library) jobs

GET /api/jobs/{id} Job state snapshot

GET /api/jobs/{id}/events SSE stream of job state

POST /api/jobs/{id}/cancel Terminate active subprocess and cancel job

PATCH /api/jobs/{id}/sections Save waveform section markers for a job

GET /api/jobs/{id}/stems/{name}.wav Stream a single stem WAV file

GET /api/jobs/{id}/stems/{name}.mp3 Transcode and stream a stem as MP3

GET /api/jobs/{id}/video.mp4 Mux the current mix with the source video (MP4 upload or YouTube) into an MP4

DELETE /api/jobs/{id} Remove job dir from disk (terminal jobs only)

Troubleshooting ffmpeg: command not found: install ffmpeg and restart with ./run.sh restart. WARNING: [youtube] No supported JavaScript runtime: install deno (brew install deno on macOS) and restart. Downloads still work without it but may pick suboptimal formats. First separation is very slow: Demucs downloads htdemucs_6s weights (~170 MB) on first run; cached afterwards. Demucs runs on CPU only: check the startup log for device=mps or device=cuda. If you see cpu, your torch install may be CPU-only. Page reloaded mid-job: the job keeps running server-side. Wait for it to finish, then resubmit. ./run.sh: Permission denied: run chmod +x run.sh.

Layout on Disk jobs/<job_id>/ └── stems/ ├── vocals.wav # the 6 Demucs stems (always present) ├── drums.wav ├── bass.wav ├── guitar.wav ├── piano.wav ├── other.wav ├── original.wav # sum of un-selected stems (subset only) └── mix.wav # ffmpeg amix of selected stems (subset only)

Job state is in-memory. Restart the server and the job list resets, but files persist on disk. Old dirs are swept automatically (TTL 24 h, configurable).

Disclaimer StemDeck is a local audio stem separation tool intended for personal study, research, and experimentation. It is not a downloading service. It does not store, cache, or redistribute any audio content. All processing runs on the user's own machine and no audio is transmitted anywhere. YouTube URL support is provided via yt-dlp as a convenience. Automated downloading may violate YouTube's Terms of Service. You, the user, are solely responsible for ensuring you have the right to process any audio you submit, complying with the terms of service of any site you download from, and respecting the copyright of the material you work with. You are also responsible for following the licenses of the underlying tools this project depends on (yt-dlp, Demucs, FFmpeg, PyTorch, and others listed in pyproject.toml). The author(s) of StemDeck provide this software "as is", without warranty of any kind, and accept no responsibility or liability for how it is used.

Code signing policy Windows releases of StemDeck are Authenticode-signed. Free code signing is provided by SignPath.io, certificate by SignPath Foundation. The signed binary is StemDeck.exe inside StemDeck-Windows-x64.zip and StemDeck-Windows-x64.NVIDIA.zip. The zip archives themselves are not signed; verify them with the .sha256 file published alongside each release asset. macOS and Linux builds are not currently signed. Team roles

Role Members

Committers Thales Pereira (@thcp)

Reviewers Thales Pereira (@thcp)

Approvers Thales Pereira (@thcp)

How signing works The executable is built from this repository by the Windows Release workflow on a GitHub-hosted runner, uploaded as a workflow artifact, and submitted to SignPath for signing. SignPath verifies the build's origin (repository, branch, commit, and build job) before the certificate is applied. Every release signing request is approved manually by an approver listed above. Privacy StemDeck does not transmit any personal data. All audio processing happens on the user's own machine. See the Disclaimer for details.

Community

Platform Link

GitHub stemdeckapp/stemdeck

Discord discord.gg/2MVsWqaPRe

Reddit r/StemDeckApp

Instagram @stemdeck

X @StemDeckApp

Website stemdeck.app (coming soon)

Environment Variables These are for development and testing. Release builds only recognize the variables marked "release".

Variable Platform Scope Description

STEMDECK_DATA_DIR all release Override the user data directory (default: platform-standard location)

STEMDECK_ROOT all release Override the app root directory (default: derived from executable path)

STEMDECK_PYTHON all debug builds only Override the Python executable path

STEMDECK_FFMPEG_URL Windows, macOS release Override the FFmpeg download URL

STEMDECK_FFPROBE_URL macOS release Override the ffprobe download URL

Contributing Issues, feature suggestions, and pull requests are welcome. See open issues for what's planned.

source