Running more than one Firefox Profile at once?

Firefox can run in different profiles, that can be setup using different plugins, for different purposes such as basic web browsing, web development, trading on ebay etc...

Is it possible to run more than one of these at a time, or does Firefox always run as a singleton?

You can start multiple instances of Firefox with different profiles using the -no-remote argument:

firefox -P <profile_name> -no-remote

However this solution as some drawbacks.

The -no-remote switch specificaly state that:

• a new instance of Firefox should be started (instead of just open another window in a running instance)
• the new instance should not accept remote commands

This implies that all Operative System integration is disabled (since this integration it's implemented using remote commands), and so, things like opening hyperlinks from other applications don't work.

To get around this issue you can open a Firefox instance without the -no-remote switch, and then open multiple other instances with -no-remote. The first instance will work as you are used to, and will open all hyperlinks from external applications. Have in mind that you cannot open two instances with the same profile.

One more point: allways use your default profile to run without -no-remote. This way you avoid to allways have to open a Firefox instance without the no-remote when you already have -no-remote instances running.

More information about -no-remote can be found here, including some discussions about this problem.

To have several Mozilla Firefox windows with different profiles open at the same time, using the newer flag -new-instance instead of -no-remote is friendlier to open web links from external programs such as Thunderbird, etc.

For example, in the properties of a desktop icon for each profile:

firefox -P <profile_name> -new-instance

See: Bug 716110 - split -new-instance flag out of existing -no-remote flag