The short version: we never see your data. Health readings stay on your iPhone; what you log lives on your iPhone and in your own private, encrypted iCloud — nowhere else. Here's the long version.
On your device, and what you log in your private iCloud
Everything Migraine Sentry knows about you is stored in a local database on your iPhone. The records you log — attacks, symptoms, medications, check-ins, settings — are also backed up to your own private, end-to-end-encrypted iCloud (Apple CloudKit), so your history survives a lost, broken or new phone. Health readings from Apple Health (sleep, heart rate, HRV and the rest) are never stored in iCloud by the app — on a new phone, Migraine Sentry rebuilds its analysis from Apple Health itself, which Apple syncs under its own protections. There is no account and no Migraine Sentry server that holds any of it; the iCloud copy can be unlocked only by your Apple ID, never by us.
What leaves your phone
Two things. First, the private iCloud backup of your logged records — encrypted, tied to your Apple ID, and invisible to us. Second, to fetch local weather and pressure forecasts, the app sends your approximate location, rounded to about 1 km, to a weather data provider. No identifier, no health data, nothing else travels with it. That's the entire network footprint of your personal data.
Permissions, and what they actually do
| Permission | Used for |
|---|---|
| Health data | Reading signals Apple Health already records. Migraine Sentry never writes to or shares your Health data. |
| Motion & barometer | Your iPhone's pressure sensor. |
| Location | Approximate position for the weather lookup above. Never stored precisely. |
| Notifications | Morning forecasts, signal nudges, and check-in / follow-up reminders. Never marketing. |
Deleting your data
Profile → Delete all data permanently erases every record after a confirmation: from your device and from your private iCloud backup. There's no company server copy to chase, because one never existed.
Deleting just the app is different: your iCloud backup remains, so reinstalling brings your history back. If you want everything gone, use Delete all data first, then delete the app.
Full details: Privacy policy.