Privacy Policy for ZoneTrainer
Overview
ZoneTrainer ("the app") is an Android application designed for heart rate zone training and real-time audio telemetry. We believe your personal fitness and health data belongs to you and only you. This policy explains how the app handles your data with strict commitment to user privacy and offline security.
1. 100% Local Data Storage
ZoneTrainer does not collect, transmit, or share any personal fitness or biometric data. All fitness data generated by the app is stored exclusively on your device within a local Room database and DataStore preferences. No external servers or cloud services are involved in processing your workout metrics.
Data Stored Locally on Your Device
| Data Type | Purpose | Storage Location |
|---|---|---|
| Training session history (duration, average BPM, zone times, optional distance) | Session history display & analytics | Local Room database |
| Heart rate zone configuration (BPM ranges) | Zone training calculations & telemetry | Local DataStore |
| Last connected Bluetooth device address | Auto-reconnect on application launch | Local DataStore |
| Target zone & alert interval preferences | Application configuration & audio alerts | Local DataStore |
| Anonymous Installation UUID | 24-hour active telemetry rate-limiting | Local DataStore |
2. Data Transmission & First-Party Backend
ZoneTrainer is built on an offline-first foundation. To verify legacy purchases and monitor general app adoption without third-party tracking networks, the app communicates strictly with our first-party, encrypted server endpoint over HTTPS/TLS (zonetrainer.goschan.xyz):
- Anonymous Device Telemetry: Once every 24 hours upon launch, the app transmits an app-scoped installation UUID solely for basic first-party analytics (measuring Daily Active Users, version adoption, and platform stability). This identifier is generated locally at install time, resets completely on app uninstallation, and is never linked to personal identity (PII), email addresses, or persistent hardware identifiers (such as IMEI, MAC address, or Android ID).
- Receipt Validation: When restoring legacy purchases for the "Premium Unlock" SKU, a cryptographic purchase token is verified against the Google Play Developer API via our server.
- Zero Health Data Leakage: All network requests contain zero heart rate readings, zero workout logs, zero GPS locations, and zero user account credentials.
3. Bluetooth & Location Permissions
ZoneTrainer uses Bluetooth Low Energy (BLE) to connect to standard heart rate monitors (chest straps, armbands). The app:
- Scans for and connects to nearby BLE heart rate monitors (GATT
0x180Dprofile) - Reads real-time heart rate data directly from the connected device
- Does not transmit Bluetooth data to any server or third party
- Does not store raw Bluetooth device identifiers beyond the last-used device address (kept locally for auto-reconnect)
Android Permissions Required
| Permission | Reason |
|---|---|
BLUETOOTH_SCAN |
Discover nearby Bluetooth Low Energy heart rate monitors |
BLUETOOTH_CONNECT |
Connect to and read real-time heart rate data from monitor |
FOREGROUND_SERVICE |
Continue heart rate tracking & voice alerts when screen is off |
POST_NOTIFICATIONS |
Display a persistent status notification during active workouts |
4. Zero Third-Party Tracking & SDKs
ZoneTrainer contains no third-party tracking SDKs, advertising networks, or data brokers (such as Firebase, Google Analytics, Mixpanel, or Meta SDK). All network traffic is strictly confined to first-party endpoints, and no user or device information is ever sold, shared, or accessible to third parties.
5. Data Retention & Deletion
All training data is stored locally on your physical device. You retain full control over your data:
- You can delete individual workout records or purge all session history at any time from within the app settings.
- Uninstalling the ZoneTrainer app permanently removes all associated local data and configuration files from your device.
6. Children's Privacy
ZoneTrainer does not knowingly collect or solicit data from children under 13. Because the app does not collect personal data from any user, no personal data from children is ever acquired or processed.
7. Changes to This Policy
If this privacy policy is updated, the changes will be published on this page with a revised "Last updated" date at the top of the policy.
8. Contact Support
If you have any questions or concerns regarding this privacy policy or ZoneTrainer's data practices, please contact support at: