ChatZilla is a free IRC client for various versions of the Mozilla browser.

It was written in JavaScript and XUL by Robert Ginda, and works with any operating system that runs on the Mozilla. ( Among other things, Mac OS, Linux, Microsoft Windows, Solaris, IRIX, BeOS, HP- UX, OS / 2 and BSD. ) The program supports popular IRC functions, including CTCP, DCC, mIRC colors, etc. The appearance of the messages can easily change via CSS. ChatZilla is delivered with the Mozilla Suite and SeaMonkey, but is also available as an extension for Mozilla Firefox and other Mozilla -based browsers. Furthermore, ChatZilla can operate with the XULRunner as a stand alone version.

Similar to mIRC can also be integrated with ChatZilla scripts that provide additional functionality. The language used here comes JavaScript to use. Since the entire Mozilla API is available, very extensive and powerful script are possible. Due to the compared to mIRC rather young age and low penetration but not quite as many scripts are available.