How to run Firefox 3 and Firefox 4 simultaneously in Windows

Most of us have upgraded to the latest version of Firefox, that is the Firefox 4 Beta which works exceedingly well and is quite a stable build. However, some people are facing problems while running their favorite add-ons on the latest offering from Firefox.

Those who want to get the best of both worlds can try and run Firefox 3 build, along with the Firefox 4 beta version simultaneously. If you try and run both the versions simultaneously it wont work because by default both of the versions will try and run on the same profile and resulting into the working of only one of the versions. But you can do a small modification to the profiles, you will be able to use both of the versions simultaneously.

Here’s how it works:

  • There is by default only one profile for the Firefox,so you have to create one more profile to make this work.
  • Hit Windows+R and type “/path/to/firefox -P profile_name -no-remote" in the box and Hit Enter.
  • Now a profile manager will be opened click on Create profile

  • Proceed to the next step by clicking next

  • Enter a Name for the profile and the default path will be chosen for saving the profile and if you want you can select a custom path as well.

  • Hit finish to complete the Profile Creation process.

  • Select the new profile and click Start Firefox. Now you can run both the versions of Firefox simultaneously.

That’s it!

UPDATE by Admin: Our TWC Forum thread The “EASY” way to use both Firefox 3 & 4, and easily switch between them may also interest you.

Posted by on , in Category General with Tags
The author is a MVP Alumni, pursuing his Computer Engineering Degree. A tech enthusiast, he blogs everything about Microsoft at You can follow him @Sagarsaw on Twitter.