Tor Messenger is a cross-platform chat program based on Instantbird, an instant messaging client developed in the Mozilla community. It sends all of its traffic over the Tor network, enabling "off-the-record" messaging automatically.
Tor Messenger is compatible with the same protocol used by Google Talk, Facebook Chat, Twitter and Yahoo, so users can tap into their existing network of contacts rather than having to rebuild it from scratch.
"Tor Messenger builds on the networks you are familiar with, so that you can continue communicating in a way your contacts are willing and able to do," said The Tor Project in a blog post.
"This has traditionally been in a client-server model, meaning that your metadata (specifically the relationships between contacts) can be logged by the server. However, your route to the server will be hidden because you are communicating over Tor."
The Tor Messenger beta is available for Windows, Mac and both 32-bit and 64-bit Linux. The Tor Project emphasised that the release is for users who would like to help with testing the product, but at the same time who also understand the risks involved in using beta software.
Tor Messenger is not the first application to offer encrypted messaging. Popular instant messaging apps like Pidgin and Adium also "off-the-record" communications. However, these require a manual setup process, whereas the Tor Messenger offers it by default.