Opening Firefox: multiple profile, multiple versions

This post answers two questions:

1. How to run multiple instances of Firefox, each using different profile?
2. How to run multiple versions of Firefox?

Running multiple instances of Firefox each using different profile:

Very easy. Just open notepad, paste below code, save it as batch (.bat) file, double click on batch file, you are done!

start "" "C:\Program Files\Mozilla Firefox\firefox.exe" -P default -no-remote

This opens Firefox with a "default" profile, which was created at the time of installing. To open with different profile just replace "default" with some other name. Very first time when you run this, as the new profile not exist yet, it allows you to create one. Create profile with same name what you have given in batch file, next time onwards it will use that profile automatically.

Tip: If you want to have multiple profiles and running batch file should ask you to select the profile, just don't create profile which has same name as you provided in batch file. This will make Firefox always to provide with an option of creating new profile or selecting existing one.

Running multiple versions of Firefox:

Even this is very easy, Install another version of Firefox in different location, create batch file as explained above, provide the correct path to Firefox executable folder, provide new profile name and you are done! So my new batch file might look like,

start "" "C:\Program Files\Mozilla Firefox2\firefox.exe" -P "ff2" -no-remote

Note: Opening profiles of one Firefox version in another version might create problems if you have Firefox addons installed. For example, if you create a profile "ff3" for Firefox 3 and install firebug in it, opening the same profile using Firefox 2 might stop you from using firebug.