Terms of Service

Effective 14 September 2026. Version 1.1.

Service provider: Optimum Paweł Kowalski

Address: ul. Pozytywistów 4/4, 20-639 Lublin, Poland

Tax ID (NIP): 712-031-17-46, REGON: 430325730

Contact: [email protected]

1. What StemPlayer is

StemPlayer (stemplayer.app, "the Service") separates an audio file you upload into up to six stems (vocals, drums, bass, guitar, piano, other) and lets you mix, mute, solo, slow down, loop and export the result in your browser. It is a practice tool. There is no account; using the Service means you accept these Terms.

2. Beta, limits and availability

The Service is offered in beta, free of charge. Separation runs on rented GPU capacity, so there are limits: a number of separations per person per day and per day for the whole Service, a maximum file size and a maximum track length, as shown in the app. Limits can change without notice. We may pause, change or withdraw the Service or any feature at any time, and we may introduce paid plans in the future; anything you have exported stays yours.

3. Your files and your rights

You keep every right to the audio you upload and to the mixes you export. We claim no rights to them and use them only to provide the Service (see the Privacy Policy for how files are handled).

You confirm that you are entitled to process the audio you upload: it is your own recording, or you hold a licence that allows this use, or the use is otherwise lawful (for example private study). You are responsible for what you do with the stems and mixes. Do not upload material you have no right to use, and do not use the Service to infringe anyone's rights.

4. Acceptable use

We may block access that breaks these rules.

5. Separation quality and warranty

Stem separation is never perfect: instruments overlap, and some bleed always remains. Results depend on the source. The Service is provided "as is" and "as available", without warranty of any kind to the extent the law allows. Nothing in these Terms limits rights you have as a consumer under mandatory law.

6. Liability

To the extent permitted by law, we are not liable for indirect or consequential loss, lost data, or loss arising from unavailability of the Service. Keep your own copies of your files: the Service is not a backup. The stems and mixes shown in the app are stored in your own browser and can be removed by the browser at any time.

7. Third parties

The Service runs on infrastructure from third-party providers of hosting, file storage and GPU computing, described in the Privacy Policy. Our sibling tool CountIn (countin.band) has its own terms; sending a mix there is your choice.

8. Changes and law

We may update these Terms; the current version is always at this address with its effective date. Polish law applies, without affecting mandatory consumer protections of your country of residence. Disputes go to the competent Polish court, unless consumer law gives you another forum. Questions: [email protected].