How to Install two versions of firefox in Windows : When creating web applications, any development must be tested in as many browsers as you wish to support.

Below is the market share of browsers last month:

As Firefox 4 was released recently, many people lost Firefox 3.6. These instructions will allow you to run multiple versions of Firefox in parallel.

Firefox uses the default profile to save all of your settings, bookmarks and addons. When upgrading Firefox, this profile is updated to use the latest version. The concept in the following tutorial is to use a different profile for each version of Firefox you wish to install.

How to Install two versions of firefox in Windows

In this example i have installed 2 versions where the main one is 10.0 and the secondary browser is 44.0

  1. Download the versions of Firefox you wish to install –
  2. If you already have a version of Firefox – go to step 4
  3. Install a version of Firefox in the normal way
  4. Close any Firefox windows
  5. Click Start > Run. Type firefox.exe -p (Windows 7 users – Open a command window and run the command from there)
  6. Create as many profiles as you have Firefox versions (in my case Profile 1 and Profile 2)
  7. Profile 1 (for Firefox 10.0) Profile 2 (for Firefox 44.0)
  8. Install old versions of Firefox in different folders but do not run them
  9. Create shortcuts to the different versions specifying the profile to use
    • For Firefox 10.0 us as below :
    • “C:\Program Files (x86)\Mozilla Firefox\firefox.exe” -p Profile1 -no-remote
    • For Firefox 44.0 us as below :
    • “C:\Program Files (x86)\Mozilla Firefox 44.0\firefox.exe” -p Profile2
  10. Done!
  11. Upon starting Firefox each version will ask you to select the profile, once selected each version will remember the profiles.
  12. Enjoy 🙂


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