name. However, because the artwork in Firefox had a proprietary copyright license at the time, which was not compatible with the Debian Free Software Guidelines, the substituted logo had to remain. In 2006, Mozilla withdrew their permission for Debian to use the Firefox name due to significant changes to the browser that Mozilla deemed outside the boundaries of its policy, changes which Debian felt were important enough to keep, and Debian revived the Iceweasel name in its place. Subsequently, on 23 September 2007, one of the developers of the GNU IceWeasel package announced that the name would be changed to GNU IceCat from IceWeasel in the next release, so as to avoid confusion with Debian's separately maintained, unrelated rebranding of Firefox. The name change took place as planned and IceCat is the current name. IceCat was ported to the Firefox 3 codebase during Google Summer of Code of 2008. Version history Distribution GNU IceCat is freely downloadable for the IA-32, x86 64, and PowerPC architectures. Both binaries and source are available, though the current build is available only for Linux. Some distributions offer binary and source packages through their repositories, such as Trisquel, Parabola GNU/Linux-libre and Fedora. IceCat is also available for macOS 10.4 and higher. Any Mac user with these versions of macOS can install IceCat through Fink. For the Mac, it is available for both IA-32 and PowerPC architectures. Unofficial builds are available for Windows (Vista or newer) and Android (2.3 or newer). Additional security and privacy features IceCat includes additional security features, such as the option to block third party zero-length image files resulting in third-party cookies, also known as web bugs (This feature is available in Firefox 1.0, 1.5, and 3.0, but the UI option was absent on 2.0). GNU IceCat also provides warnings for URL redirection. In version 3.0.2-g1, the certificate of a certificate authority CAcert.org has been added to the list of trusted root certificates. Concern about that decision has been raised in a discussion on the savannah-hackers-public mailing list. The GNU LibreJS extension detects and blocks non-free non-trivial JavaScript. IceCat also has functionality to set a different user agent string each for different domains in about:config. For example, setting a mobile user agent string for a desired DNS domain would make it possible to view the mobile version of a website on a desktop operating system. Licensing Gnuzilla is available under the MPL/GPL/LGPL