Tundra IRC is an IRC client written entirely in Java, to ensure compatibility with any platform. It sports a clean, tabbed interface, and supports multiple servers and channels. The primary reason it was written was to provide a suitable IRC client for Mac OS X.
What's new in this version:
Fixed a problem that occurred when messaged after closing a tab
Added a shell startup script
Implemented alternate nicks during connection
Updated interface (Menu bar at top of screen on Macs)
Operating System Requirements:
This product is designed to run on the following operating systems:
Well there are plenty of OS X IRC clients. You can run X-Chat via X11 or use the aqua port. It is a tabbed IRC client and personally I don't like Java apps. But it is well done anyway.