WeeChat

WeeChat is a fast, light and extensible chat client, with a text-based user interface.

WeeChat is:

modular: a lightweight core with optional plugins
multi-protocols architecture (mainly IRC)
multi-platforms: Linux, Unix, BSD, GNU Hurd, Haiku, macOS and Windows (WSL and Cygwin).
extensible with C, Python, Perl, Ruby, Lua, Tcl, Scheme, Javascript and PHP
fully documented and translated into several languages
a free program released under the terms of the GNU General Public License version 3
an active project with a large community for scripts.