Mozilla Open Source Web Development

Browser VM

One of the great things about virtual machines is you can test on a virtual machine, destroy it, and recreate it in pristine condition in a matter of seconds. You can do this with browsers as well. Before I mentioned PortableApps is a great thing to have on your USB drive. Well, you can also just unzip a copy to your desktop each time you want a clean version of Firefox. So keep your good install for yourself, and perhaps create another with extensions you want to test, or if you just want to test your site against an older version of Firefox. I believe it will still use plugins installed on your computer, but extensions, prefs, etc are totally separate. So each install is pristine. I keep a copy around of 1.0.x and 1.5.x as well as 2.0. So each time I want to test on an older version I can just run those. The prefs won’t mess anything up since it’s a fresh copy. You can keep your latest and greatest Firefox install with all your extensions and settings alone. This allows me to ensure everything works good in different versions without having to risk my preferences to older versions, or have to go through install/uninstall.

You can get various versions of Firefox here. Just download and extract to your desktop or some other easy to access place. I keep a copy of all the major versions around. Very handy.

I should note you can only run 1 version at a time, even though they use different preferences. Not sure if this is a fixable bug, something with serious work that just isn’t worth the effort, or something that XULRunner will take care of. Update: apparently you can, see comments below.

Unfortunately I don’t think there is a version of PortableApps for Mac/Linux users. So it may be Windows only for now.

In case you missed it, you can test IE7 via VirtualPC thanks to Microsoft.

5 replies on “Browser VM”

I think using the -noremote command line switch should let you launch more than one instance of Firefox at once.

Actually, the command line switch to let you run additional Fx instances is -no-remote, and it doesn’t work for versions prior to 2.0. For versions prior to 2.0, you have to set the environment variable MOZ_NO_REMOTE to 1. For example, in a (Windows) batch file you could do this:

start “” “C:\Program Files\Mozilla Firefox\firefox.exe” -p profilename

For Linux “portable” installs, you can use the the compressed tarball at:

For other versions/locales change the URL a bit or go here. You can get all versions starting from 1.0 (the same is true for all Mozilla products).

Extract this archive to a place you like, CD into it and run ./firefox.

I don’t use Mac’s, so I don’t know if the dmg files which can be found on the same site are just installers, or archives which you can extract to a different location, but Smokey Ardisson already provided a link for portable Mac apps.

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