WeeChat is a fast, light and extensible chat client, with a text-based user interface.
WeeChat is designed to be light and extensible: a lightweight core with optional plugins.
Plugins and scripts can be dynamically loaded and unloaded at any time.
Almost everything is a plugin, for example:
WeeChat brings a lot of innovative features, which makes it different from other console/terminal based chat clients.
Look by yourself (the list is not exhaustive):
IRC plugin implements the protocol as described in the RFCs 1459 and 2812.
It comes with many built-in features, such as:
External interfaces (graphical or text) can connect to a running WeeChat.
They communicate with WeeChat using the relay protocol.
A list of interfaces is available on this page.
WeeChat is translated into several languages and has a comprehensive documentation, also translated.
There is an excellent support for users. Try it if you have any questions!