Hazel Stack does not collect, transmit, or share any personal information. Everything it knows about your training stays on your phone.
Hazel Stack is an interval and circuit training timer that lets you run preset routines or build your own and keeps a log of your sessions. The pages that follow describe, in plain language, what the app does and does not do with the things you type into it.
None. There is no account, sign-up or login. The only things you type into the app are an optional display name, a weekly minutes goal and the names of routines you build, and those never leave the device.
For the app to work, the following is kept in the operating system's local storage, on your phone, and nowhere else:
None of it is uploaded. Uninstalling the app removes every byte.
Hazel Stack requests no runtime permissions. It does not use the camera, microphone, location, contacts, photos or notifications. The Android release build does not even declare the Internet permission.
None. The app works fully offline and makes no network requests of any kind. The movement library and preset routines are bundled inside the app, so nothing is downloaded after you install it.
No analytics, advertising, crash-reporting or tracking SDKs are integrated, and there are no in-app purchases. The app is built with open-source Flutter libraries for its local database (sqflite), settings storage (shared_preferences), charts and animations. None of them send data anywhere.
Hazel Stack is a general-audience fitness timer and is not directed at children under 13. Because it collects no personal information from anyone, it collects none from children either.
All of your data is on your device, so you are always in control of it. You can delete individual routines inside the app, or clear everything by using "Clear storage" in your phone's app settings or uninstalling Hazel Stack. We hold no copy, so there is nothing for us to export or delete on your behalf.
If anything in this policy changes, the date at the top of the page will be revised, and material changes will appear in the app's release notes.