Privacy Policy
Stem Splitter ("the app", "we") splits songs into separate instrument tracks (stems) so you can practice, mix and record with them. This policy explains what data the app handles, why, where it goes and how to delete it. We keep it short because the app collects very little.
The short version
- No account, no email, no password. The app creates a random identifier on your device to link your songs to you.
- Audio you choose to split is uploaded to our server and processed by a third-party AI service (Replicate) to separate the instruments. The results are stored on our server until you delete the song.
- Recordings you make over a track with the microphone stay on your device. They are never uploaded.
- No advertising, no analytics SDKs, no tracking across apps or websites, no selling of data.
- Deleting a song in the app deletes it and its stems from our server.
What we collect and why
| Data | Why | Where it lives |
|---|---|---|
| Random device identifier (UUID) | To tell your songs apart from other users' without an account. | Your device (Keychain) and our server. |
| Device language and time zone; whether the build is a development build | To show the app in your language and for debugging. | Our server, attached to the identifier. |
| Audio you upload: audio files, the audio track of videos you pick, files downloaded from links you paste | To separate the song into stems. This is the app's core function. | Our server (source file and resulting stems) and, during processing, Replicate. |
| Song title, artist and duration read from the file's own tags or the file name | To label the song in your library. | Our server and your device. |
| Purchases, subscription status and token history (what you bought, when, balances and what tokens were spent on). No payment card details: Apple handles payment. | To give you the tokens and subscription you paid for and to restore them on a new device. | Our server and RevenueCat, attached to the identifier. |
| Microphone recordings ("takes") | To record your own part over a song, if you choose to. | Your device only. |
| Mixer settings (volumes, trims, key, tempo, renamed titles) | To restore your setup when you reopen a song. | Your device only. |
| Server request logs (IP address, request time, endpoint) | To keep the service running, rate-limit abuse and diagnose errors. | Our server, rotated after a short period. |
The app does not access your contacts, location, calendar or photo library beyond the single video you pick with the system picker. Access to the microphone and photos is requested only when you use those features, and you can revoke it in iOS Settings at any time.
Third parties that process data
- Replicate, Inc. (United States) runs the AI model that separates the instruments. The audio you upload is sent to Replicate for processing and the separated stems are returned to our server. Replicate's handling of data is described in its own privacy policy at replicate.com/privacy.
- RevenueCat, Inc. (United States) manages in-app purchases and subscriptions. It receives the identifier and your App Store purchase records so we can tell which subscription or token pack you bought. See revenuecat.com/privacy.
- Hetzner Online GmbH (Germany) hosts our server, where songs, stems and the identifier are stored.
- Apple processes payments for subscriptions and token packs, and provides the App Store and iOS features the app relies on, such as the file and photo pickers and the share sheet. What you do with the share sheet (for example saving an exported mix to Files or sending it to another app) is governed by the app you send it to.
We do not share your data with anyone else. If an error happens on our server, an automated message with technical details (never your audio) is sent to our internal monitoring channel.
Demo songs
The app ships with a few demo songs that are already split into stems. They are the same for every user and are not linked to you.
Your content and copyright
Only upload music you own or have the right to use. You keep all rights to your audio; we use it solely to provide the separation you asked for and never for training models, advertising or anything else.
Retention and deletion
- Songs and stems stay on our server until you delete the song in the app (swipe left on it in your library). Deletion removes the source file and all stems immediately.
- Everything on your device (cached stems, recordings, settings, the identifier) is removed by deleting the app, or by "Delete all data" in the app's Settings on development builds.
- The identifier and the data attached to it on our server can be erased on request: write to us at the address below. Because there is no account, please include a description of your songs so we can find them.
Children
The app is not directed at children under 13 and we do not knowingly collect data from them.
Security
All traffic between the app and our server is encrypted (HTTPS). Your identifier is stored in the iOS Keychain. Stems are served through our server with unguessable links.
Your rights
Depending on where you live, you may have the right to access, correct, export or erase your data, or to object to its processing. Since the app holds almost no personal data, the practical way to exercise these rights is to delete your songs in the app or contact us.
Changes
If we change how the app handles data, we will update this page and the effective date above. Significant changes will be announced in the app.
Use of the app is also governed by our Terms of Use.
Contact
IE Denis Zhesterev
stem@priles.dev