XChat
Xchat is a popular
free IRC client for
Unix and Unix-like
operating systems, like
Linux, with a version for
Windows. Its
graphical user interface uses the
GTK+ graphics toolkit, featuring the use of
tabbed windows to represent
IRC server connections, channels and private messages.
XChat is highly extensible, featuring a plug-in architecture able to accept Perl, Python and binary (usually C) modules. It is released under the GNU General Public License.
Homepage: http://www.xchat.org