Fenster: Fasting Timer

A fasting clock. Hours on, hours off. No streaks, no scores, no invented biology. Your data stays on your phone.

Fenster is a fasting clock. You open a window, you close a window. That is the whole app, done properly.

THE CLOCK Pick a protocol: 16:8 and 12:12 free forever, 14:10, 18:6, 20:4, OMAD, and custom hours with the lifetime unlock. The ring counts your window. Go past your target and the clock counts overtime instead of pretending you finished.

HONEST BY DESIGN No streaks. No scores. No "fat-burning zones." No ketosis claims a clock cannot measure. Fasting stages are shown as rough bands with real physiology and honest limits, because your body is not a progress bar.

EVERYWHERE Home screen widget with the live ring. Dynamic Island and Lock Screen Live Activity. Siri, Shortcuts, the Action Button, and a Control Center control: start a fast without opening the app. Close a finished window straight from the notification.

APPLE HEALTH, MINIMALLY Health can fill your profile (age, height, weight). Fenster writes exactly one thing back: the weight you choose to save. Fasts stay in Fenster. Apple has no fasting type, and we do not invent one.

SAFETY FIRST Clear guidance about who should not fast, visible stop rules, a gentler mode with shorter windows, and a check-in if a window stays open too long. Fenster is a clock, not a clinic.

PRIVATE No account. No tracking. No servers. Your data lives on your device, in English and German. More languages coming.

One optional payment. $9.99, lifetime, done.