Last updated August 20, 2026
Every fast you log — start time, end time, protocol, streaks, badges — is stored only in a local database on your device. Fern has no backend server and no analytics service, so this information is never transmitted anywhere, never seen by us, and never sold or shared with anyone. If Fern's Home Screen widget or Live Activity shows your progress, that's the same on-device data, shared only between the app and its own widget through Apple's standard App Group mechanism — still entirely on your device.
If you delete the app, this data is deleted with it. Settings also has a "Delete all local data" option that clears it instantly without deleting the app itself.
Fern can optionally read your weight and sleep data from Apple Health, if you choose to connect it in Settings. This is entirely opt-in — Fern never asks at first launch — and read-only: Fern never writes anything to Health. This data is used only on your device, to show trends alongside your fasting history (for example, comparing weeks with more consistent fasting against your logged sleep). It is never transmitted off your device, and Fern doesn't retain a separate copy of it — each time Fern shows you a Health-based trend, it reads fresh from Health at that moment.
You can revoke this access at any time in the Health app or in iOS Settings → Privacy & Security → Health → Fern, or disconnect it directly from Fern's own Settings screen.
Fern's reminders (fast start/end, eating-window closing, stage transitions) are scheduled locally on your device using iOS's standard notification system. There is no push notification server — Fern has nothing to send from, and nothing about when your fast starts or ends is ever transmitted anywhere to make these work.
If you subscribe to Fern+, the purchase is handled entirely by Apple through the App Store. Fern never sees or stores your payment details — it only asks Apple's systems "is this subscribed, yes or no" to unlock the relevant features. Managing or cancelling your subscription happens through your Apple ID account settings, the same as any other App Store subscription.
Fern is not directed at children and does not knowingly collect any information from children, on-device or otherwise.
If this policy changes, the date at the top will update, and any material change will be described here in plain language rather than buried in legal text.
Questions about this policy or how Fern handles data: see the Support page.