IceCat is a free and open source web browser produced by GNU. It has a GPL, MPL/LGPL tri-license license and is made to work on several platforms, and employ all free licensed code.
GNU IceCat, formerly known as GNU IceWeasel, is a free software rebranding of the Mozilla Firefox web browser distributed by the GNU Project. It is compatible with both the GNU/Linux and Mac OS X (10.4 and 10.5) operating systems.
The GNU Project keeps IceCat in synchronization with upstream development of Firefox while removing all trademarked artwork. It also maintains a large list of free software plugins and add-ons, and includes a few security features not found in the mainline Firefox browser.