Privacy Policy
Offstem ("the app") splits songs and videos into four stems — vocals, drums, bass, and other — entirely on your iPhone. This policy describes what the app does with your data. The short version: Offstem does not collect, transmit, or store any personal data. All audio processing happens on your device.
1. No data collection
Offstem does not collect any personal information. There is:
- No account — no sign-up, no login, no profile.
- No analytics — no usage tracking, no crash-reporting SDKs, no telemetry.
- No advertising — no ad SDKs, no cross-app tracking, no identifier-for-advertisers (IDFA).
- No third-party data sharing — we do not sell, rent, or disclose your data to anyone, because there is nothing to disclose.
Apple may provide us with standard, aggregate sales and crash information through App Store Connect (for example, the number of downloads or a crash log). This is Apple's system, not ours — we have no way to tie it to you as an individual.
2. Everything runs on your device
Audio separation is performed on-device using a Core ML model. Your audio files, the stems they produce, and any preview waveforms are processed and stored only on your iPhone. They are never uploaded, never sent to a server, and never leave your device. You can delete a separation (stems and the original file) from the Library at any time, which removes those files from storage.
Because of this, Offstem works fully offline and in Airplane Mode.
3. Network use
Offstem makes one optional, one-time network connection: on first launch, it downloads the machine-learning model (~135 MB) that performs the separation. The download is Wi-Fi-only by default, resumable, and the model is required for the app to function. A newer version of the app may update this model the same way.
Apart from this model download, the app makes no network connections — in particular, none during separation.
4. Files you process
Offstem can open audio (M4A, MP3, WAV, AAC) and video (MP4, MOV) files that you pick from the Files app. The app reads these files on your device and never sends them anywhere. You are responsible for processing only audio you own or have permission to use.
5. Children
Offstem does not collect personal information from anyone, including children.
6. Changes to this policy
If this policy changes, we will update this page and the "Last updated" date above. Because the app itself does not collect data, substantive changes are unlikely.
7. Contact
Questions about this policy: support@offstem.app.