Fast.IO
Track elapsed, remaining, overtime, and phase markers with quick start/stop and start-time editing.
Intermittent fasting, made calm
Build a steady fasting routine with timer, hydration, and insights.
Fast.IO helps you stay consistent with focused sessions, progress trends, water tracking, widgets, Live Activities, and Apple Watch sync.
Fast.IO is a wellness and habit-tracking app. It does not provide medical advice.
Free + one-time Pro unlock
No subscription. Start free and unlock advanced intervals, deeper history and stats, widgets, watch features, and personalization once.
- Preset and custom fasting intervals
- Session timeline, history, and trends
- Hydration goals and reminders
- iCloud continuity across devices
Core features
Stats & Calendar
Review week, month, year trends with completion rates, average duration, and interval popularity.
Water Tracking
Set daily goals, quick-add water, log custom amounts, and monitor hydration during fasting windows.
Widgets + Live Activities
See fasting status on Home and Lock Screen and keep progress visible with Live Activities.
Apple Watch
Start fasts and log water from your wrist with sync between watch and phone.
Knowledge + Achievements
Learn fasting basics and stay motivated with milestone achievements and consistency tracking.
Free vs Pro at a glance
Free covers your core timer flow. Pro unlocks the full interval library, custom intervals, deeper history, advanced stats, and ecosystem extras.
See full comparisonPrivacy-first by design
Your fasting and hydration logs stay tied to your Apple ecosystem, with iCloud-backed continuity for your own devices.
Read privacy policyPopular questions
Is this medical advice?
No. Fast.IO is a wellness and habit-tracking app and does not provide medical advice.
Is Pro a subscription?
No. Pro is a one-time purchase. You can restore purchases using your App Store account.
Does it work with Apple Watch and widgets?
Yes. The app includes Home/Lock Screen widgets, Live Activities, and an Apple Watch companion experience.