Auto-detect interval training for runners. More than just a timer.
Run faster and train smarter with the original Fartlek auto-detect interval training app. Built by runners for runners. For both Apple Watch and iPhone.
Train with classic intervals, HIIT, Tabata and Fartlek in one powerful running app.
More than just a simple timer. Switch to Fartlek mode and let FiT detect your speed, automatically converting your run into structured intervals.
No reaching for your device.
No pressing buttons.
Just automatic recording of your activity.
FiT displays your progress live, with colour-coded feedback showing how hard you’re running and when you’re recovering. The beautiful Dual Progress Ring shows progress for the current interval and the overall workout, keeping you motivated throughout.
Analyse every interval with detailed pace, heart rate, cadence and distance metrics.
Share your runs with friends with full syncing to Strava and Apple Health.
Key features:
Auto-detection of spontaneous intervals in Fartlek mode
Live colour-coded effort feedback
Powerful interval timer for structured workouts
Detailed interval metrics and analysis
Integrated with Strava and Apple Health
NEW! Advanced effort levels automatically detect sprint, hard, moderate and easy effort during your run.
Run free.
Train smart.
Let the app do the rest.
Happy fartlekking!
Subscription Terms
FiT offers an optional auto-renewable subscription. Payment will be charged to your Apple ID account at confirmation of purchase. The subscription automatically renews unless auto-renew is turned off at least 24 hours before the end of the current period. You can manage or cancel your subscription at any time in your Apple ID account settings.
Terms of Use:
https://www.apple.com/legal/internet-services/itunes/dev/stdeula/
Privacy Policy:
https://www.iubenda.com/privacy-policy/39192677
Ratings & Reviews
This app has not received enough ratings or reviews to display an overview.
Version 2.5 introduces workout analysis charts, with new visualisations showing your target and actual performance for each interval.
Improved workout summaries provide cleaner, more informative workout reviews with key metrics highlighted.
Additional bug fixes and improvements enhance performance and reliability.
Version 2.5
The developer, Richard English, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Privacy practices may vary based, for example, on the features you use or your age. Learn More
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
Provider
Richard English
Size
71.5 MB
Category
Health & Fitness
Compatibility
Requires iOS 26.0 or later.
iPhone Requires iOS 26.0 or later.
Mac Requires macOS 26.0 or later and a Mac with Apple M1 chip or later.
Apple Vision Requires visionOS 26.0 or later.
Apple Watch Requires watchOS 10.6 or later.
Location
This app may use your location even when it is not open, which can decrease device battery life.