Forget about Firefox 3.0! Even though the successor of Firefox 2.0 is yet to be finalized and approximately a month away from general availability, Mozilla is moving full steam ahead to the next step in the open source browser. In this context, a pre-release version of Firefox 3.1 Alpha 1 has been made available for download via Mozilla's FTP servers as a nightly built. As the tradition goes with Firefox, the browser, even at this early stage in its development, it is designed to tailor not only Windows, but also Linux and Mac OS X. The first downloads of Firefox 3.1 pre-Alpha 1 went live on May 22, 2008.

Mozilla is offering Firefox 3.1 pre-Alpha 1 under the general codename of Minefield, and has not come up with a fully fledged development label as was Gran Paradiso for Firefox 3.0. Instead the Minefied codename is designed to point out that Firefox 3.1 pre-Alpha 1 is nothing more than a trunk build of the open source browser.

According to Mozilla's official Minefield Start Page: "This is not a final or pre-release version. This program is provided without any guarantees of stability, so please use it at your own risk. It is recommended that you back up your profile regularly, as there may be bugs that corrupt your data."

At this stage in its development, Firefox 3.1 is very similar to Firefox 3.0, at least on the surface, with the majority of the changes focused on the backend infrastructure. According to Mike Shroepfer, Mozilla Vice President of Technology, Firefox 3.1 will sport all the features that could not be integrated into Firefox 3.0 in order to meet the June 2008 launch deadline. Firefox 3.1 will take the performance of the open source browser to the next level, delivering an evolved Smart Location Bar (Awesome Bar), but also XHR, native JSON DOM bindings. Of course, nothing is set in stone, and changes could also impact top layers such as the graphical user interface and not only under-the-hood components.

Via its FTP servers, Mozilla is offering the following versions of Firefox 3.1 pre-Alpha 1 for download: firefox-3.1a1pre.en-US.linux-i686.complete.mar, firefox-3.1a1pre.en-US.linux-i686.tar.bz2, firefox-3.1a1pre.en-US.mac.complete.mar, firefox-3.1a1pre.en-US.mac.dmg, firefox-3.1a1pre.en-US.win32.complete.mar, firefox-3.1a1pre.en-US.win32.installer.exe and firefox-3.1a1pre.en-US.win32.zip.

As far as Firefox 3.0 is concerned, the Release Candidate 1 (RC1) build for Windows is available for download here.
Firefox 3.0 Release Candidate 1 (RC1) for Linux is here.
Firefox 3.0 Release Candidate 1 (RC1) for Mac is here.