http://wikipewt4n75trifcse2ggaieot27svognl7idu6xmmqn37kf64rvsyd.onion/index.php/TorChat
There are versions available for Microsoft Windows and Linux. A beta version is in development for Mac OS X, and a cross-platform version called jTorChat is being developed in Java. In TorChat every user has a unique alphanumeric ID consisting of 16 characters.