Demucs.net

What is this website?

Demucs.net is an independent web front end for Demucs: upload a mixed song, run open-source v4 (Hybrid Transformer) on cloud GPUs, and get stems such as vocals, drums, and bass without installing Python, PyTorch, or CUDA. The terms state it is not affiliated with or endorsed by Meta or the authors. Sign-in is required, and jobs are billed in credits by length. It fits previewing and exporting stems. For changing weights or an offline pipeline, use the official GitHub repository.

Core features

• Choose 2 stems (vocals and instrumental), 4 stems (vocals, drums, bass, other), or 6 stems (with separate guitar and piano).
• Three v4 weight sets: Standard, Best quality, and six-stem; the model authors note that the piano stem is the weakest of the six.
• Solo or mute each stem in the browser, then download tracks one by one or as a ZIP.
• Accepts MP3, WAV, FLAC, M4A, and OGG; the free tier is limited to about 6 minutes and 50 MB.
• Accounts that pass abuse checks receive 15 credits per month; subscriptions or credit packs raise concurrency and retention, and Studio adds WAV/FLAC.
• The site says audio is not used for training: the source file is deleted when the job ends, and stems are kept for 24 hours, 7 days, or 30 days depending on the plan.

Typical use cases

• When practicing a cover or karaoke, use a 2-stem split for an instrumental and listen for bleed before downloading.
• When a remix or mix needs a relatively clean vocal, preview breaths and reverb tails on the site, then export.
• When following a drum or bass part, isolate the rhythm section to transcribe or sample—only if you have the right to process the original.
• When voice-over and music are mixed in a finished video, split first, then duck or replace the music.
• When you have no local GPU setup and only need a few songs split, process them and download the results.

Who is it for?

• Musicians or editors who split tracks occasionally and can accept cloud queues and a credit meter.
• People who want to hear v4 before deciding whether to install it locally.
• Anyone whose delivery must be lossless and who needs to check whether Studio WAV/FLAC is worth enabling.
• A poor fit: people who lack rights in the original recording but plan to publish or sell the stems—separation does not create new copyright.
• A poor fit: offline or self-hosted GPU work, or engineering that needs to modify the model for batch research.

How does it compare with similar tools?

Separate “hosted website” from “the model,” then choose:

• Install cost: this site hosts the published v4 weights; local Demucs needs your own Python stack and GPU. The site also mentions desktop options such as Demucs-GUI and Ultimate Vocal Remover, which still require installation and are more GPU-sensitive.
• Named models: many vocal-remover sites do not disclose the backend; here the labels are htdemucs, htdemucs_ft, and htdemucs_6s.
• Quality numbers: the site cites SDR for fine-tuned v4 versus Spleeter on MUSDB18-HQ. Those are public-benchmark scores for the model, not a guarantee for every song or every hosted job.
• Licensing: the code is MIT. The weights were trained on data that includes non-commercial tracks, and the site states it is legally unresolved whether weights inherit dataset terms. Stem use still follows the original recording’s rights.

FAQ

Q: Is Demucs.net the official Demucs app?

A: No. It is an independent site that runs open-source Demucs. Official code lives at facebookresearch/demucs on GitHub.

Q: Can I start a separation without signing in?

A: You cannot submit a job. Sign in with Google or confirm your email; after checks, the account receives 15 credits each month. If you pick a file before signing in, the site can keep it in the browser and continue after login.

Q: Can I use the stems commercially just because I split them?

A: Splitting does not grant new rights. You must be allowed to process what you upload. On the training-data license question for the weights, the site asks you to assess significant commercial use yourself rather than treat it as cleared.

Q: Is there a Demucs v5?

A: According to the site, the latest public release is still v4 (the maintained 4.1 fork is still the v4 model). Products labeled v5 are not an official version of that project.