Your privacy.

Effective 21 September 2026

Zonometry is an iPhone app by Philipp Seyfi. It helps you understand your training using data you choose to share from Apple Health. You do not need an account.

Health data stays on your device

With your permission, Zonometry reads workouts, heart-rate readings, workout effort, recorded workout routes, running metrics, and VO₂ max. With permission, date of birth and biological sex help personalize heart-rate estimates and cardio-fitness reference bands. The app processes this information on your iPhone to display your training history and zones. We do not receive it on a server, sell it, or use it for advertising.

If you save an effort rating, the app asks for permission to write that rating and associate it with the workout in Apple Health. Your preferences and locally stored app data remain on your device and may be included in device backups according to your Apple settings.

Optional weather

Weather is optional. When you choose a city, its coordinates are sent to Open-Meteo to retrieve weather. City searches are sent to Open-Meteo’s geocoding service. If you choose to use your location, the app requests location access and rounds the coordinates to two decimal places before requesting weather.

Open-Meteo receives the approximate coordinates or city search, together with ordinary network information such as your IP address. No workouts, heart-rate readings or other Health data are included. Open-Meteo states that its troubleshooting logs may contain coordinates and are deleted after 90 days. Open-Meteo handles these requests under its own privacy policy. You can turn weather off or choose a city instead of using your location.

Your choices

You control Health access in the Apple Health app: open your profile, then Apps and Zonometry. You can change location access in iPhone Settings. Disconnecting Health in Zonometry clears the app’s loaded Health data; it does not delete Apple Health records or revoke permissions. Reconnecting may load the data again if access remains enabled.

You can remove local app data by deleting the app. Health records, including effort ratings saved to Health, are managed separately in Apple Health.

No advertising or tracking SDKs

Zonometry does not include advertising, third-party tracking SDKs or a user-account system. This website does not use advertising cookies or analytics scripts. Cloudflare hosts the website and processes technical request data, including IP addresses, to deliver and secure it under its privacy policy.

Research videos

Research pages can embed videos from YouTube. The player loads only after you choose to play it, using YouTube’s privacy-enhanced embed domain. Playing a video connects your browser to YouTube, which processes technical request and playback information under its privacy policy. You can read the article without loading the player.

When you contact us

If you email support, we receive your email address and whatever you include so we can respond. Please share only the information needed to explain your issue. We use support correspondence to help you and resolve problems, not for advertising.

Questions and changes

For privacy questions or requests concerning information you have sent us, contact support. Updates to this policy are published here with their effective date.