Signal-Android
A private messenger for Android.
Signal Android is the official open-source Android app for Signal private messaging, it keeps your texts, voice calls, and video calls encrypted end-to-end so only you and the recipient can ever read them.
Signal Android is the official open-source Android app for the Signal private messaging service. Signal lets you send messages, make voice calls, and have video calls over your phone's internet connection (WiFi or mobile data) with end-to-end encryption — meaning only you and the person you're talking to can read your messages, not Signal's servers or any third party.
The app is designed around the idea that strong privacy should be the default, not an optional setting you have to dig for. You don't need to change any settings or flip any switches — the encryption is always on. It handles text messages, high-quality audio calls, HD video calls, and group chats.
You would use this if you care about the privacy of your communications and want an alternative to standard SMS or other messaging apps that may store or have access to your conversation content. It's popular with journalists, privacy-conscious individuals, activists, and anyone who wants to keep their conversations confidential.
The app is built in Kotlin (Android's primary programming language) and is available through the Google Play Store or as a direct download from signal.org. The source code is open, meaning anyone can inspect how it works and verify the privacy claims. The project is licensed under the GNU AGPLv3, which means any modified versions must also be open-source.
Where it fits
- Audit Signal's encryption implementation to independently verify its privacy and security claims by reading the actual app code.
- Study how Signal implements end-to-end encrypted messaging in Kotlin to learn secure communication patterns for your own Android app.
- Contribute bug fixes or improvements to the official Signal Android app by running and building it locally.