HexChat is an IRC client based on XChat for Linux , but unlike XChat it’s completely free for both Windows and Unix-like systems.
HexChat was originally called XChat-WDK which in turn was a successor of freakschat.
Easy to use and customizable interface
Cross-platform on Windows, OS X, and Unix-like OSes
Highly scriptable with Python and Perl
Translated in multiple languages
Fully open source and actively developed
Multi-network with auto-connect, join, and identify
Spellcheck, Proxies, SASL, DCC support and more