Climb

An intermittent fasting tracker for iPhone and Apple Watch.

It can’t lose your fast. Climb stores the instant you started, never how long it’s been — so there is no running total to drift, and nothing to lose.

Download on the App Store →

Free · iPhone and Apple Watch · requires iOS 26.5 or later

Climb's main screen, 13 hours 24 minutes into a fast, with the Fat burning rung highlighted on a seven-stage ladder — Mid-fast

An iPhone Lock Screen with Climb's Live Activity counting a running fast — Lock Screen

Climb's history screen showing a four-day streak and six completed fasts — History

Why that matters

Most fasting apps count upwards. Climb works backwards from when you started.

Storing elapsed time is why other trackers lose fasts after a restart, a reboot, or a daylight-saving change — the most common complaint in the category. Climb derives every number from the start instant and the current time, every time you look. Change timezone mid-fast and it stays right.

A ladder, not a ring

Seven stages, so progress has somewhere to go.

The colour climbs amber to violet as the hours pass — on the phone, the widget, the Lock Screen and the watch face alike.

Fed0h
Settling3h
Glycogen burning8h
Fat burning12h
Ketosis16h
Deep ketosis24h
Autophagy48h

Typical timings, drawn from research on averages — not measurements of you.

The rest of it

Where you already lookLive Activity on the Lock Screen and Dynamic Island, Home Screen widgets, and Apple Watch complications on four families.

Keeps countingEvery surface is handed the start instant rather than woken to be told the time, so none of them stall while the app is closed.

Edit anythingMove a start time back, log a fast you forgot, extend a goal mid-fast, or undo an end you didn’t mean.

Your data, portableExport the whole history as JSON and import it back. No lock-in, because there is nothing to lock into.

Privacy

Nothing leaves your phone.

No account. No sign-in. No analytics. No advertising identifiers. No third-party SDKs. Climb makes no network requests at all — there is no server for your data to reach even in principle. See the privacy policy, which is short because there is very little to say.