BitchX is a modified clone of the popular ircII client, and is available for almost all UNIX OS's as well as Win9X/NT and OS/2.
bnIRC is a modular IRC framework and a good curses client to go with it.
ccirc is a not-so-simple irc client, written in shell scripts. It features advanced scripting, generic irc commands, multiple windows and colored display.
EPIC4 is derived directly from EPIC3, which was itself derived from IRC-II which is currently maintained by Matthew Green, and includes in whole all the additions included in the "plus" clients by Jeremy Nelson and all of the modifications in the "mod" clients by Jake Khuon. Read more
ERC is an IRC client for Emacs. It supports the RFC 1459 (well, most of it) and has other nice features, like faces support, pals lists and more. Read more
F-IRC supports multiple servers, scrollback, and all the basic features one can expect from an IRC client.
GeoIRC is intended to be a stable, customizable, usable, scriptable, good-looking IRC client. The development team hopes to make it the client of choice for a significant portion of the IRC community.
ircII is an IRC client that runs under most UNIX platforms. It comes in source form and is completely free of any charges or fees. The ircII project is a group of people who maintain the source code, incorporating fixes and new features. Read more
irker is a specialized IRC client that runs as a daemon, allowing other programs to ship IRC notifications by sending JSON objects to a listening socket.
Irssi is a terminal based IRC client for UNIX systems. It also supports SILC and ICB protocols via plugins. Features include: Autologging, formats/themes, configurable keybindings, paste detection, perl scripting, irssi-proxy, and more. Read more
nsirc is a tiny IRC client for Unix-like systems, available under the terms of the GNU General Public License. It is based on sirc version 2.211, written by Roger Espel Llima. Unlike the original sirc, it has a full-screen multi-window user interface, somewhat similar to the well-known irssi.
Perl LIRC Client
Perl LIRC Client is a replacement of irexec and irxevent found in the standard LIRC distribution.
Rhapsody IRC is small, fast, portable and easy to use, yet it is full featured. The thing that separates it from the crowd is its intuitive menu driven user interface.
Riece is an IRC client for Emacs. It supports multiple server profiles, custom window layout, and other nice features. Riece can be dynamically extended by add-on (plugin) modules. By default, 30 add-ons are available.
ScIRC is an IRC client written in Scheme. The interpreter chosen for this project is GUILE, GNU's Ubiquitous Intelligent Language for Extension.
ScrollZ is an IRC client based on ircII with numerous added features like userlist, cdcc, colors and more. Read more
sirc is an IRC (Internet Relay Chat) client for Unix programmed and programmable in perl.
WeeChat is a fast and light IRC client for many operating systems. Everything can be done with a keyboard, and it is customizable and extensible with scripts. Read more
Xaric is a UNIX irc client similar to (and forked from) BitchX and ircII.