The Tor is the free software that lets users browse the Internet anonymously and mostly used by activists, journalists and to conceal their online activities from prying eyes. The Tor Instant Messaging Bundle is a real time anonymous chat system, that will route all of your chat data through the Tor’s encrypted network, which uses proxy servers to hide the identities of its users. The client itself will be built on top of Instantbird, an open source instant messaging service. The first experimental release won’t include ‘Off The Record’ (OTR) capability.
Source: https://thehackernews.com/2014/02/tor-instant-messaging-bundle-new.html