How To Change the User Agent String in Firefox

Do you need a quick way to change the user agent string in Firefox for a specific website? Choose the string that you need from a preset list (or from custom entries) with the User Agent Switcher extension.

Note: Works with Firefox, Flock, SeaMonkey, and Songbird.


Before adding the extension to our browser we tested the user agent string at and got a positive I.D. result for Firefox.



Once you add the extension to Firefox you can access the alternate user agent string in two ways. The first is through the tools menu…

Note: The user agent string will automatically reset back to the default each time you restart Firefox.


And the second is using a toolbar button. Choose the method that works best for you.


For the first test we chose Internet Explorer 8.


Refreshing the page tested positive for IE 8.


Next we chose the Yahoo! Slurp search robot…once again a perfect result.


Moving on we chose iPhone 3.0. As before another positive identification.


To keep things interesting we set the user agent string for Internet Explorer 6. Testing positive for IE 6 and Windows XP here…


And also testing positive at the extension author’s website.



You can create, edit, and delete current user agent strings or use the import/export functions.



The User Agent Switcher extension provides a quick and easy way to change the user agent string for those less than cooperative websites. For those wanting to add additional user agent strings visit this website (available in xml file format).


Download the User Agent Switcher extension (Mozilla Add-ons)

Verify the User Agent String for your browser

Akemi Iwaya is a devoted Mozilla Firefox user who enjoys working with multiple browsers and occasionally dabbling with Linux. She also loves reading fantasy and sci-fi stories as well as playing "old school" role-playing games. You can visit her on Twitter and .