IntervalGuide

IntervalGuide is a free interval timer app for iPhone, Apple Watch, Android, and Wear OS. It pairs with any Bluetooth heart rate monitor for live BPM and heart rate zones during boxing, HIIT, and Tabata workouts — no account, no cloud.

At a glance

Platforms: iPhone (iOS 16+), Apple Watch (watchOS 8+), Android, Wear OS
Best for: Boxing, HIIT, Tabata, circuit training, and running intervals
Heart rate: Any Bluetooth LE monitor, including Polar, Garmin, and Wahoo
Watch apps: Companion apps — they need your phone nearby
Price: Free with ads, with an optional Premium subscription
Privacy: No account, no cloud sync, nothing stored on Tremia servers. The free version shows ads via Google AdMob.
Health sync: Apple Health on iPhone, Health Connect on Android
Languages: English and German

Features

Custom Interval Timers

Build any workout structure — rounds, rest periods, warm-up, cool-down. Fully customizable.

Real-Time Heart Rate

Connect any Bluetooth LE heart rate monitor and see your BPM live during workouts.

Watch Companion

See your timer and heart rate on your wrist with the Apple Watch and Wear OS companion apps, paired with your phone.

Boxing Bell & Audio Cues

Authentic boxing bell sounds and voice prompts so you never miss a round change.

Heart Rate Zones

Track which zone you're training in — fat burn, cardio, or peak — in real time.

No Account, No Cloud

The timer, heart rate, and workout history work offline and stay on your device. Tremia runs no servers for your workout data. The free version shows ads.