Last updated: 19 June 2026

Zone 2 Guardrail is an Apple Watch app that warns you when your heart rate drifts above your Zone 2 ceiling during a workout. It is built to run entirely on your device. The developer does not collect, store, transmit, sell, or share any of your data.

Data the app accesses

To do its job, the app uses Apple's HealthKit framework to access the following, all of which stays on your Apple Watch and iPhone:

• Heart rate (read): read live during a guarded session so the app can alert you when you exceed your Zone 2 ceiling.
• Date of birth (read): read once to estimate your age and set a sensible default heart-rate ceiling. You can override this at any time.
• Workouts (write): when you grant permission, a completed guarded session is saved as a workout so it appears in the Health app. This is optional — the app guards your heart rate with read access alone.

You control these permissions in the Health app and can revoke them at any time.

Data the app collects or transmits

None. Zone 2 Guardrail has no servers, no accounts, no analytics, no advertising, and no third-party tracking. Your health data is never sent off your device by this app. It is processed locally and is never used for advertising, marketing, or data mining, and is never disclosed to any third party.

Purchases

The optional one-time "Pro Unlock" purchase is processed entirely by Apple through the App Store. The app never sees or stores your payment details. Apple's handling of your purchase is governed by Apple's Privacy Policy.

Children

The app is not directed at children and does not knowingly collect any personal information from anyone, including children.

Changes to this policy

If this policy changes, the updated version will be posted on this page with a new "Last updated" date.

Contact

Questions about this policy? Contact the developer at [email protected].