Subcategory: IRC clients
Programing language: Emacs-Lisp
rcirc – a next generation InternetRelayChat client. It blends seamlessly with the rest of Emacs, it’s tight, fast, and doesn’t light up like a christmas tree. rcirc also has sane defaults. There is little or no reason to customize it because it does what you want by default (except that many people still do).
rcirc is part of GNU Emacs since release 22.0.
Screenshot author: Roman Lagunov, Source: Wikimedia.org; License: GNU GPL