Skip to the content.

Privacy Policy

Last updated: 2026-05-11 Effective date: 2026-05-11

This Privacy Policy explains how the FastMask Android application (“FastMask”, “the app”, “we”, “our”) handles your personal information. FastMask is an unofficial, open‑source client for Fastmail masked email addresses. It is not affiliated with or endorsed by Fastmail Pty Ltd.

1. Data Controller

The data controller responsible for this app is:

2. What Data the App Processes

FastMask processes only the minimum data needed to function as a Fastmail masked‑email manager:

Data Where it is stored Why it is processed
Fastmail API token Locally on your device, encrypted via Android EncryptedSharedPreferences (AES‑256‑GCM for values, AES‑256‑SIV for keys) To authenticate JMAP API calls to api.fastmail.com on your behalf
Masked email addresses, descriptions, domain/URL associations, activity timestamps In memory while the app runs; persisted only on Fastmail’s servers To display, create, edit, and search your masked emails
Selected language Locally on your device via Android DataStore To remember your language preference between sessions

We do not collect or process any of the following:

For users in the European Economic Area, the legal basis for processing the data above is Article 6(1)(b) GDPR — performance of a contract: we process your data because it is strictly necessary to provide the masked‑email management functionality you requested by installing the app and logging in.

4. Data Sharing and Recipients

We do not share, sell, rent, or otherwise transfer your personal data to third parties.

The only network destination contacted by the app is api.fastmail.com (Fastmail’s JMAP API), which is reached directly from your device over HTTPS/TLS. The app uses Android’s Network Security Config to restrict trust for that hostname to the system certificate authority store.

Your Fastmail account, including all masked emails, is governed by Fastmail’s own privacy policy: https://www.fastmail.com/about/privacy/.

5. International Data Transfers

Because the app talks only to Fastmail and stores everything else locally on your device, transfer of your personal data outside your country is determined entirely by Fastmail’s infrastructure and is subject to their privacy practices.

6. Data Retention

7. Your Rights

To the extent applicable law (such as the GDPR or the UK GDPR) grants you rights over your personal data, you have the right to access, rectify, erase, restrict, port, or object to processing of your data, and the right to lodge a complaint with a supervisory authority.

Because we have no servers, you can exercise the deletion and rectification rights yourself at any time:

For any other questions or to exercise your rights regarding the small amount of data processed locally by the app, contact pawel@orzech.me.

8. Security

No security measure is perfect. If you believe you have found a vulnerability, please follow the responsible disclosure process described in SECURITY.md.

9. Children’s Privacy

FastMask is not directed at children under 18, and we do not knowingly process data from children. The app is rated 18+ on Google Play.

10. Changes to This Policy

We may update this policy from time to time. Material changes will be announced through a new app release and reflected in the “Last updated” date at the top of this document. The current version is always available at https://pawelorzech.github.io/FastMask/privacy.html.

11. Open Source

FastMask is open source under the MIT License. You can inspect the full source code, the network security config, and the proof that no third‑party tracking SDK is bundled at https://github.com/pawelorzech/FastMask.

12. Contact