XChat, commonly written X-Chat or xchat, is one of the most popular IRC clients for Unix-like systems. It is also available for Microsoft Winows and Mac OS X (available as a Mac OS X native version called X-Chat Aqua, or an X11 version maintained by the Fink project). It has a choice of a tabbed or tree interface, support for multiple servers, and a high level of configurability. Both command line and graphical versions are available, although use of the graphical version far outweighs use of the command line version. It is licensed under the GNU General Public License and uses the GTK+ toolkit for its interface.