Privacy Policy

Last updated: March 24, 2026

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Overview

Stack My Trails is a personal fitness visualization app that reads your workout routes from Apple Health (iOS) or Health Connect (Android) and displays them on a map. You can also record new workout routes or draw routes manually. Your data stays on your device. We do not collect or store any user data on external servers. Network requests are limited to the platform's geocoding service for place name lookups, to Apple's directions service (iOS) or optionally to OpenRouteService (Android) for route drawing, and to Apple Health or Health Connect when recording workouts (see sections below).

Data We Access

Workout Routes (Apple Health / Health Connect)

We read workout route data (GPS coordinates, timestamps, and activity types) from Apple Health on iOS or Health Connect on Android. On iOS, weather metadata (temperature and conditions) is also read when available. This data is used solely to:

Workout data is imported explicitly by you and stored locally in an on-device database. We never read or write health data in the background.

When you record a trail, the GPS route is tracked using your device's location services in the foreground. The recorded workout is saved to the local database and also written to Apple Health (iOS) or Health Connect (Android) so it appears in your fitness history. The screen stays awake during recording to ensure continuous GPS tracking.

On Android, we request read and write access to Exercise Sessions and Exercise Routes via Health Connect. We also request access to historical health data (older than 30 days) so you can import your full workout history. On iOS, we request read access to workout routes and write access to workouts via Apple HealthKit.

Location

We use your device's location services for the following purposes:

  1. Reverse geocoding — converting GPS coordinates of your workout routes into human-readable place names (e.g., city and region). This is done via the platform's built-in geocoding service (Apple on iOS, Google on Android), which means the coordinates of your workout route centers are sent to Apple's or Google's servers for lookup. We cache the resulting location names locally on your device to minimize these requests. No other data is transmitted. The handling of this data is governed by Apple's Privacy Policy or Google's Privacy Policy, respectively. On Android, location permission is required for reverse geocoding.
  2. Show My Location on the map — when you manually enable this option in the Settings tab, your current position is displayed on the stacked trails map. This helps you discover new or unvisited routes in your area. This feature is off by default and can be toggled on or off at any time. Your live location is used only for on-screen display and is never stored or transmitted.
  3. Trail recording — when you start recording a trail, the app tracks your GPS position in the foreground using high-accuracy location services. The recorded route is stored locally and optionally written to Apple Health or Health Connect. Location tracking stops immediately when you stop recording. We do not track your location in the background.
  4. Route drawing — the app includes a route drawing tool that lets you create walking routes by placing waypoints on the map. On iOS, waypoint coordinates are sent to Apple's directions service (the same service that powers Apple Maps) to compute walking routes between points; the handling of this data is governed by Apple's Privacy Policy. On Android, if you provide your own OpenRouteService API key in Settings, waypoint coordinates are sent to the OpenRouteService Directions API (operated by HeiGIT gGmbH, Heidelberg, Germany) to compute walking routes between points. This is entirely opt-in: no data is sent to OpenRouteService unless you explicitly enter an API key. Without a key, the drawing tool uses straight lines between points instead. The handling of coordinates sent to OpenRouteService is governed by the HeiGIT Privacy Policy and the OpenRouteService Terms of Service.

Photo Library

When you choose to save a poster image, we request permission to write to your photo library. We do not read or access your existing photos.

Data Storage

All data is stored locally on your device:

Data Export and Backup

You can export your trail data to a local file for backup purposes. This file is stored on your device and shared only if you explicitly choose to do so. The exported file contains your workout routes and is signed for integrity verification. Importing a backup merges data into the local database.

Data We Do NOT Collect

Third-Party Services

Stack My Trails does not use any third-party analytics, advertising, or tracking services. The app operates entirely offline after installation, with the following exceptions:

Data Deletion

You can delete all imported trail data at any time from the Settings tab within the app. Uninstalling the app removes all stored data from your device.

Children's Privacy

Stack My Trails does not knowingly collect data from children under 13. The app does not collect any personal data from any user.

Changes to This Policy

We may update this privacy policy from time to time. Any changes will be reflected in the "Last updated" date above.

Contact

If you have questions about this privacy policy, contact us at [email protected].