There are plenty of messenger applications with support for end-to-end-encryption, so only you and the person you're talking to can read the conversation. But Briar is a bit different - it uses the Tor network to send and receive messages. The app has now entered beta, and you can download it from the Play Store.
In addition to using the Tor network, Briar has a few interesting features. In the event that your network (or government) blocks Tor, you can send encrypted messages using Bluetooth or ad-hoc Wi-Fi.Read More
Tor-based "Briar" messaging app enters public beta was written by the awesome team at Android Police.