In last post I have shown how to change user agent on chrome browser but most of us does use Mozilla Firefox. We can change user agent on Firefox simply using an extension and by geeky way too from about:config page.
First of all here are the iPhone and Android browser user agent string that you will need in this tutorial.
iPhone User agent
Mozilla/5.0 (iPhone; U; CPU like Mac OS X; en) AppleWebKit/420+ (KHTML, like Gecko) Version/3.0 Mobile/1A543a Safari/419.3
Android User agent(Nexus)
Mozilla/5.0 (Linux; U; Android 2.2; en-us; Nexus One Build/FRF91) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1
User Agent Switcher
Open this link in Firefox browser and click on Add to Firefox button to install User Agent Switcher add-on. Restart the Firefox browser once the extension get installed.
Now check Firefox menu. Go to Tools->Default user agent. You can choose the predefined user agent strings from the menu or you can add one of yours to the list by clicking edit user agent from the menu.
From about:config page in Firefox
Open the about:config page in Firefox from and address bar, right click in the list area.
Click New–>String, enter string value as “general.useragent.override” and value as the user agent of your choice.
Here as an example enter the iPhone user agent string mentioned above.
If you want to change this string later you can always go to about:config page and search for general.useragent.override from filter and edit the value. If you want to delete this newly added string(general.useragent.override) permanently, right-click it and click on reset from menu.