How to Change the User-Agent for Firefox

There are a whole bunch of reasons you may want to trick a web site into thinking you’re using a browser other than Firefox. Maybe you’re a web developer and need to see what a site looks like in another browser. Maybe a site only allows certain browsers and you don’t have access to them. Whatever your reason, this guide will show you how to use the User-Agent Switcher and Manager add-on for Firefox so that you change the user-agent that Firefox uses to identify itself to a different one.

  1. Head over to the User-Agent Switcher and Manager add-on page and install it as you would any other Firefox add-on. Once it’s installed you’ll see a new icon in the upper-right corner of Firefox.
  2. the firebox toolbar

  3. When you click the User-Agent Switcher and Manager icon a large window will pop-up.
  4. the the User-Agent Switcher and Manager add-on main window

  5. To change the User-Agent for Firefox, start by clicking the Browser menu from the upper-left corner of the User-Agent Switcher and Manager pop-up window. From that list, choose the browser you whose user-agent you want to use. In this example, I’m choosing Safari.
  6. the User-Agent Switcher and Manager browser menu

  7. Next, click the Operating System menu (it’s right next to the Browser menu). I’ve opted to use iOS.
  8. the User-Agent Switcher and Manager OS menu

  9. Now select the version of the browser you want to use.
  10. the User-Agent Switcher and Manager list of iOS options

  11. If you only want the current window (or tab) to use the alternate user-agent, click the Window button. If you want to use the new user-agent across all windows and tabs, click the Apply button.
  12. the User-Agent Switcher and Manager button list

  13. The User-Agent Switcher and Manager icon will change, indicating the new user-agent that your current window/tab is using.
  14. the User-Agent Switcher and Manager toolbar icon with iOS displayed

  15. Click the Refresh Tab button to reload the page you’re currently viewing. This will send the ‘new’ user-agent to the web site and it will load as if you’re using that browser.
  16. Change the User-Agent for Firefox being applied

  17. As you can see in the screenshot below, YouTube now thinks my browser is Safari for iOS (iPhone/iPad) and it has loaded the mobile version of YouTube.com.
  18. screenshot of the mobile version YouTube being rendered in Chrome

  19. When you’re done and want to switch back to the default Firefox user-agent, re-open the User-Agent Switcher and Manager pop-up window and click the Restart tab if you selected Window back in step #6. If you selected Apply so that the new user-agent was applied to all of your tabs and windows, instead of clicking Restart, click the Reset button.
  20. the User-Agent Switcher and Manager button list with Restart highlighted

  21. That’s it! You can now use Firefox to ‘trick’ web sites into thinking you’re using a browser that you’re not actually using.

For more Firefox tips and tricks, be sure to scroll through the Firefox category.


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