Mozilla.org recently released Firefox 1.5. Firefox runs under a huge number of OSes and GUI environments. It is officially designed and maintained to run under Microsoft Windows NT 4 or later, Windows 98 or later, MacOS X 10.2 and later, and various recent versions of Linux. Numerous contributors have provided versions of Firefox built for even more operating systems.

Firefox 1.5 runs under all of the major versions of Microsoft Windows in use today:

Windows 2003 Server (NT 5.2)	Windows XP (NT 5.1)
Windows ME	Microsoft Windows 2000
Windows 98	Windows NT 4

Firefox 1.5 also runs on modern Apple Macintosh computers under MacOS X 10.2 and later:

Mac OS X 10.3.4

Because Firefox is so portable and the code is open source, it was the first major third-party application ported to Apple's MacOS X for x86 (not yet released).

It is nearly impossible to list all of the different versions and distributions of Linux that Firefox runs under. Mozilla.org provides a generic x86 Linux version for download that will run under most current Linux versions. Many Linux distributors compile their own version and optimize it for their specific target software and hardware environments.

Suse Linux	Ubuntu Linux 5.10
Mandrake Linux (Thanks to MsPyro for this screen shot!)	Redhat Linux 9 (thanks to Ameya Sohoni)
Xandros Linux

With Suse Linux and Xandros, Firefox 1.5 downloaded, uncompressed, and ran right out of the box. Ubuntu 5.10 took a little bit of messing around with to get it to work.