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.
StemDeck is free and does not accept any money, sponsorship, or funding from anyone listed below. I share these makers and artists and communities purely for the joy of pointing you toward wonderful people doing beautiful work. Go meet them ❤️
| Category | Name | What they do | Link |
|---|---|---|---|
| Artists & Creators | Joao Gaspar | Producer, film scorer, touring/session musician | @jay_glaspar |
| Artists & Creators | Killah Trakz | Industry Secret Villain and Media Influencer | @killahtrakz |
| Artists & Creators | More Notes Less Talk | Gear-focused creative project with a raw, tape-recorded identity | @morenoteslesstalk |
| Artists & Creators | Analog4Lyfe | Analog gear specialist | @analog4lyfe |
| Artists & Creators | Dead röses | Cork-based punk rock band | @dead_rosesband |
| Instrument Builders & Repair | Dlima Guitars | Custom guitars and basses | @dlimaguitars |
| Instrument Builders & Repair | Lisbon Guitar Works | Handmade guitars in Lisbon | dlimaguitars.com |
| Instrument Builders & Repair | Kris Luthier | Instrument repair and restoration | @krisluthier |
| Music Gear | Empress Effects | Boutique effects pedals | empresseffects.com |
| Music Gear | Thomann | Large music-equipment retailer | @thomann.music |
| Music & Karaoke Technology | Beltr | Local, subscription-free karaoke software | beltr.app |
| Music & Karaoke Technology | Seratone | TV-based karaoke system | seratone.audio |
| Media & Community | slashCAM | Camera, video, and post-production media | @slashcam.de |
| Media & Community | r/bass | Bass-player community | r/Bass |
| Writers & Storytellers | Alexandre Borges | Portuguese writer, screenwriter, and cultural commentator | Books & author profile |
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.
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.
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. FFmpeg, the Demucs model, config, and logs live in a data/ folder next to StemDeck.exe, not in AppData; move or copy the whole extracted folder anywhere and it keeps working. On first launch the app verifies the bundled Python runtime and downloads FFmpeg and the Demucs model (~170 MB) into that folder. Subsequent launches skip this and start in seconds. Everything is self-contained; no Python or system dependencies required. Your job/library data stays in its usual location (~/Documents/StemDeck by default) and is relocatable anytime from Settings → StemData location.
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. The optional on-demand lead/backing vocal split runs the UVR-MDX-NET Karaoke 2 model via audio-separator, trained as part of the Ultimate Vocal Remover project by Anjok07. 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.
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
rustup target add aarch64-apple-darwin # Apple Silicon
rustup target add x86_64-apple-darwin # Intel
# Build Apple Silicon
ARCH=arm64 scripts/macos/make-runtime-pack.sh
ARCH=arm64 scripts/macos/make-app.sh
ARCH=arm64 scripts/macos/make-dmg.sh
# Build Intel (requires Rosetta 2 and an x86_64 Python)
ARCH=x64 scripts/macos/make-runtime-pack.sh
ARCH=x64 scripts/macos/make-app.sh
ARCH=x64 scripts/macos/make-dmg.shThe .app lands at desktop/src-tauri/target/<target>/release/bundle/macos/StemDeck.app. The DMG lands at .build/macos-dist/StemDeck-macOS-<arch>.dmg.
To run a fresh build directly without the DMG:
open desktop/src-tauri/target/aarch64-apple-darwin/release/bundle/macos/StemDeck.appIf macOS blocks the app with a Gatekeeper prompt, run:
xattr -dr com.apple.quarantine desktop/src-tauri/target/aarch64-apple-darwin/release/bundle/macos/StemDeck.appNote: 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.
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.
git clone https://github.com/stemdeckapp/stemdeck stemdeck && cd stemdeck
./run.sh setup # installs ffmpeg + uv, runs uv sync
./run.sh startOpen 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.
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 5Open http://localhost:8000.
run.shis 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 5git clone https://github.com/stemdeckapp/stemdeck stemdeck && cd stemdeck
uv sync
uv run uvicorn app.main:app --reload --timeout-graceful-shutdown 5
--timeout-graceful-shutdownbounds 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 compose -f build/docker-compose.yml up --buildStems 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:edgeOn 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.
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 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?- 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+wheelgives 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
Loopto enable. Use+/-/FitorCtrl/Cmd+wheelto 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
| 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. |
STEMDECK_SSL_CERT |
(none) | PEM certificate; set with the key below to serve https directly. |
STEMDECK_SSL_KEY |
(none) | PEM private key for the certificate above. |
STEMDECK_HTTPS_PORT |
(none) | Serve https on this port in addition to the main listener. Set by the desktop app; see below. |
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).
Transpose is built on AudioWorklet, and browsers grant that only to a
secure context. https:// and localhost qualify. A plain
http://192.168.1.20:8000 does not, so a phone reaching StemDeck over plain
http gets working playback and a key control that cannot do anything. There is
no fallback worth shipping: driving the same DSP from a ScriptProcessorNode
measured around 5% of the audio missing, because that node type drops buffers
on its own at every size.
So a server that other devices will use terminates TLS, one of three ways:
- A reverse proxy (SWAG, Nginx Proxy Manager, Traefik, Caddy). The usual
self-hosted shape, and the best one if you already run it. StemDeck reads
X-Forwarded-Protoand the RFC 7239Forwardedheader, so an https browser over a plain-http upstream hop is recognised as secure and served normally. - StemDeck itself, by pointing
STEMDECK_SSL_CERTandSTEMDECK_SSL_KEYat a certificate and key. uvicorn serves them directly; no extra package is installed for this. - A private overlay network such as Tailscale, whose addresses are already https.
Reaching a plaintext non-local origin with none of those in place is refused with a 403 that explains this, rather than served as an app that is quietly half-broken. Loopback is always served, so turning this on can never lock the host out of its own server.
The desktop app does the same thing without being configured, because it has two audiences that need opposite things.
- Plain http on
127.0.0.1for its own window. Loopback is already a secure context, so nothing is lost, and it is the only scheme that works: a self-signed certificate would raise a warning page the app window has no way to click through. - https on the LAN, port 8443 by default, for phones and other computers. This is the address Settings shows and the QR code points at.
Both listeners serve the same process, so there is one library, one queue and one Demucs worker either way.
The certificate is generated on your own machine the first time you enable
network access, and lives in <data>/certs/ beside jobs/ and
settings.json. Nothing is shipped in the download: a certificate in the
release would publish its private key to everyone who downloaded it, which is
worse than plain http because it looks secure. It is regenerated automatically
when your machine's addresses change or the certificate is close to expiring.
Because it is signed by nobody, your phone will show a "your connection is not private" warning the first time. Tap Advanced, then Continue. Once per device, per computer. Settings says so, in red, next to the toggle.
| 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) |
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.
Transpose is greyed out on another machine: the pitch stage is built on AudioWorklet, which browsers only expose on a secure context. https:// and localhost count. A plain http://192.168.x.x does not, so a client opening StemDeck over the network is never given the API and transpose cannot work there. Changing the speed still works on such a client, but it resamples instead, so the key moves with it.
Three ways to get a secure context, in order of least effort:
- Tunnel to localhost. On the client:
ssh -N -L 8000:localhost:8000 user@host, then openhttp://localhost:8000. The origin is now localhost, so everything works, including transpose. - Tailscale Serve.
tailscale serve 8000on the host publishes StemDeck on your tailnet over real HTTPS with a genuine certificate, no warnings and nothing to install on the client beyond Tailscale itself. Note the plain Tailscale IP (100.x.y.z) is not a secure context; it has to go throughserve. - Any HTTPS reverse proxy in front of StemDeck: Caddy, nginx, or a tunnel like Cloudflare Tunnel.
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.
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).
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.
StemDeck is Apache-2.0.
Every download ships a THIRD_PARTY_NOTICES.txt and a licenses/ folder. licenses/INDEX.txt lists each packaged Python dependency with its version and license, and each one's full license text sits beside it. That inventory is generated from the packaged interpreter at build time, so it describes what actually shipped rather than what was expected to.
FFmpeg is a GPL build. StemDeck downloads it and runs it as a separate executable, so it does not change StemDeck's own license, and THIRD_PARTY_NOTICES.txt carries the written offer of source for the exact build your platform receives.
| Platform | Link |
|---|---|
| GitHub | stemdeckapp/stemdeck |
| Discord | discord.gg/YhCKsjhcwB |
| r/StemDeckApp | |
| @stemdeck | |
| X | @StemDeckApp |
| Website | stemdeck.app |
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 |
Issues, feature suggestions, and pull requests are welcome. See open issues for what's planned.