Kiiro at a glance
| What it is | A running and training analytics app for Apple Watch workouts |
|---|---|
| Price | Free. Paid premium features are planned; the core will stay free. |
| Requires | iPhone with iOS 18 or later. Workouts come from Apple Watch through Apple Health. |
| Sports | Built for running. Cycling, swimming and every other Apple Health workout type are included. |
| Languages | English, French, German, Italian, Japanese, Korean, Portuguese, Russian, Spanish |
| Setup | Connect Apple Health and your existing workouts sync automatically. No manual uploads, no extra hardware. |
| Age rating | 16+ |
| Made by | endurance101 OÜ, Tallinn, Estonia |
| Download | Kiiro on the App Store |
Kiiro is spelled with two i's and pronounced "KEE-ro", with a long "ee". The name comes from Estonian, where kiirus means speed and kiire means fast; Kiiro is made in Tallinn.
Why we built it
Your watch tracks everything. Most apps answer that with more charts. We wanted the opposite: an app that says what the numbers mean and what to do next, without a sports science degree. We are a small team building the tool we wanted for our own training.
What Kiiro shows you
- Training load: whether you are doing too much, too little, or about right.
- Heart rate zones: whether easy runs were easy and hard runs were hard.
- Route comparison: whether you are getting faster on the routes you repeat.
- VO2 max trends, resting heart rate, HRV and running form.
- Goals, streaks, personal bests, full training history, and friends to train alongside.
The science behind it
Kiiro gives every workout a training load from your heart rate, relative to your own resting and maximum heart rate. It compares your acute load, a 7-day weighted average, with your fitness level, a 42-day weighted average, and turns the difference into a load balance and a named status from Undertrained to Overtrained. Heart rate is analyzed in five zones. VO2 max values are the estimates your Apple Watch records in Apple Health. The feature pages explain each calculation.
How Kiiro handles your data
- Kiiro reads workouts from Apple Health only after you give permission, and you can withdraw it in iOS Settings at any time.
- Workout data, including GPS routes, is stored on our servers so routes can be matched and trends calculated.
- The written insights in the app are generated with AI (Anthropic's Claude). Only anonymized, aggregated statistics such as training load trends and workout summaries are sent for that. Your name, email, account details and location data are never shared, and your data is not used to train AI models.
- You can review and delete your data. The privacy policy has the full detail.
Contact
Questions, feedback or press inquiries: [email protected].
