Privacy Policy

Last updated: 26 May 2026

This policy describes what data the Open Bitcoin Tracker Android application ("the app") processes, stores, and transmits. The app is published as open-source software under the MIT License.

1. Summary

The app does not collect personal data. There are no user accounts, no analytics, no advertising identifiers, and no telemetry. All data you enter into the app remains on your device.

2. Data stored on your device

The following information is stored locally in the app's private storage and is not transmitted to any server operated by the developer:

  • Stack names and Bitcoin balance amounts you enter.
  • Application preferences and display settings.
  • Optional PIN or biometric unlock configuration, held in the Android Keystore.

Android auto-backup to Google Drive is disabled for this application, so locally stored data is not copied to Google's servers via that mechanism.

3. Network requests

To display market data and on-chain information, the app makes requests to the following third-party services. No account identifier, device identifier, or tracking parameter is attached to these requests.

  • Kraken — real-time BTC price data (WebSocket).
  • mempool.space — block height, median fees, and block estimates.
  • Coin Metrics — historical network hashrate.
  • European Central Bank — daily fiat reference exchange rates.

These providers will necessarily receive the IP address of the requesting device. Their processing of that information is governed by their respective privacy policies.

4. Data not collected

The app does not collect, transmit, or store any of the following:

  • User accounts, sign-in credentials, or email addresses.
  • Analytics or product-usage data (e.g., Firebase Analytics, Sentry, Mixpanel).
  • Advertising identifiers or advertising SDKs.
  • Off-device crash reports.

5. Permissions

The app requests the following Android permissions:

  • Internet — required to retrieve market data and mempool information.
  • Biometric authentication (optional) — when enabled, the app uses Android's BiometricPrompt API to unlock locally. Biometric data is managed by the Android operating system; the app never receives or stores it.

The app does not request access to contacts, location, camera, microphone, or general file storage.

6. Source code

The complete source code of the app is publicly available and may be independently audited, built, or modified under the terms of the MIT License.

Repository: github.com/Max-Hodler/open-bitcoin-tracker

7. Children

The app is not directed to children. Because it does not collect personal data, it does not knowingly process personal data of children of any age.

8. Changes to this policy

If this policy is updated, the revised version will be published on this page and the "Last updated" date above will be modified to reflect the date of the change. Material changes to data-handling practices, if any, will be reflected here.

9. Contact

Questions regarding this policy may be submitted as an issue on the project repository: github.com/Max-Hodler/open-bitcoin-tracker/issues.