Fartlek Interval Trainer

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 color-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.

Analyze 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 color-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