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 |
2. Data Transmission (Anti-Piracy)
To protect the app's monetization model and ensure valid premium access, the app performs a one-time cryptographic verification of your purchase:
- Receipt Validation: When you purchase the "Premium Unlock," a cryptographic hash of the Google Play purchase token is sent to our private validation server (
zonetrainer.goschan.xyz). - Data Security: This request contains no personal information, heart rate data, or location data. It is used solely to verify the transaction's authenticity against the official Google Play Developer API.
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 Telemetry or Analytics
ZoneTrainer does not use any analytics SDKs, advertising networks, crash reporting services, or cloud tracking frameworks (such as Firebase, Google Analytics, or Mixpanel). No data is shared with any third party under any circumstances.
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: