HexChat is an IRC client based on XChat, but unlike XChat it’s completely free for both Windows and Unix-like systems. Since XChat is open source, it’s perfectly legal. For more info, please read the Shareware background. HexChat was originally called XChat-WDK which in turn was a successor of freakschat.
mIRC is a popular Internet Relay Chat client used by individuals and organizations to communicate, share, play and work with each other on IRC networks around the world. Serving the Internet community for over two decades, mIRC has evolved into a powerful, reliable and fun piece of technology. Free for 30 days, after which you need a user license that costs $20.