Open Source Threema Alternatives
A curated collection of the 1 best open source alternatives to Threema.
The best open source alternative to Threema is Signal. If that doesn't suit you, we've compiled a ranked list of other open source Threema alternatives to help you find a suitable replacement.
Threema alternatives are mainly Data Security & Privacy. Browse these if you want a narrower list of alternatives or looking for a specific functionality of Threema.
Private messenger for Android that uses your data connection, with encryption always on for messages, voice and video calls.

Signal is a messenger that runs over your phone's data connection, whether WiFi, 4G or 5G, instead of the carrier messaging channel. Its privacy-preserving technology is always enabled, so there is no secure mode to remember to switch on before a conversation starts.
This repository holds the Android client. The same service has separate iOS and desktop repositories, and the Android app is distributed through the Play Store and as an APK from the project website.
Day to day, what the app offers is deliberately ordinary.
- Messaging: High-fidelity messages sent and received anywhere in the world at no cost.
- Calls: HD voice and video calls between users.
- Beta channel: A Play Store testing track for people who want builds before release.
- Translations: Localization is contributed through the community forum.
- Bug reports: GitHub issues track defects, and existing ones should be searched first.
Newcomers to the codebase are pointed at a simple bug before anything larger, and feature ideas are expected to be raised on the unofficial community forum for discussion before implementation. Troubleshooting questions go to the support center and deeper documentation lives in the wiki. The distribution includes cryptographic software, so the README carries an export classification notice that matters to anyone redistributing the app across borders.