How To Display Firefox Mobile View Of Websites On A PC

It is easy to display Firefox mobile view – to request the mobile version of websites in Firefox even when using a PC or laptop.

Many websites offer a mobile friendly version of the page if you are browsing from a phone or tablet.

Why Use Firefox Mobile View?

The mobile version of a website is usually less graphically intensive and may make use of excerpts to ensure that pages are quicker to load – and do not use up as much of your precious monthly data allowance.

Here are some more reasons why you may prefer to visit the mobile version of sites like Wikipedia, Facebook and Google etc – even if you are using the desktop PC version of Firefox:

  • If you have very slow broadband (e.g. 2G/3G) then browsing mobile versions of websites can significantly speed up web browsing
  • You may prefer the streamlined look of some mobile sites which offer a simpler interface – less clutter and videos etc so easier to read the content
  • Some providers offer high/unlimited data plans for mobile devices but not for home broadband on PCs – imitating a mobile device when browsing on a PC may allow you to take advantage of those higher mobile limits
  • Web developers may want a quick way to check how quickly their site performs from a mobile perspective (although the HTML rendering will not be the same as a genuine mobile device – for better results, Google offer a Mobile Friendly Test site as a free online check)

Firefox Mobile View Switcher

Mobile View Switcher is a simple Firefox add-on to tell websites that your version of Firefox is actually running on an iPhone with iOS 11, although you can change this later if required to simulate an Android phone etc.

It adds a ‘phone’ icon to the Firefox toolbar (top right of Firefox) – click the icon to toggle the Firefox Mobile View feature between on (orange icon) and off (black icon).

mobile view switcher add-on
Mobile mode On (orange icon)

Download it from Mozilla Add-ons here. After installation there is nothing to configure, you should see the new phone icon appear in the toolbar – it is set to Off by default.

Clicking the phone icon turns ‘Mobile View’ On (as shown below) or Off for all pages – if you want to see the change applied to the current page you may need to refresh it (press F5).

Note that if you restart Firefox, the add-on remembers its previous setting i.e. if you had Mobile View set to On before, it will still be On after restarting Firefox or your computer.

How Mobile View Switcher Works

The add-on works by changing the value of the User Agent which identifies the web browser. Whenever a browser requests a page, it sends the user agent to the web server – if the user agent is of a mobile browser, the web server will return that version of the site (if there is one).

The add-on overrides the standard desktop Firefox user agent.

When you toggle Firefox Mobile View mode On, the value of the user agent is, by default, set to iPhone with iOS 11 – so web servers think you are using Firefox on an iPhone and serve up the mobile page.

If you toggle it Off, it changes the value of the User Agent back to the original (i.e. no override so the standard desktop Firefox user agent is used).

Below is an image of Wikipedia showing how much the mobile view differs from desktop view – less clutter, no sidebar and fewer images:

Firefox mobile view

Configuring The Add-On Options

Most users will have no need to change the add-on’s default mobile user agent of iPhone with iOS 11. But, if for some reason you want to change it e.g. to an Android device, you can do so in the Options:

Right click on the phone icon and choose ‘Manage Extension’ to open the add-on Options as shown below:

mobile view options

Here you can enter a new user agent string – in this example I’ve set it to an Android tablet but you can use any user agent you like.

Tip: you can find various Firefox Mobile user agent strings at a number of websites such as Udger.

Just click on the type of device and Android version you want and then copy/paste that user agent string into the add-on’s Options as shown above. Your new string will be used in future when you turn Mobile View on.


Firefox Mobile View is a simple add-on to make Firefox request the mobile version of a website, if it exists, and it is easy to switch the function on or off.

There are other Firefox add-ons which let you switch the user agent to one of many (e.g. to another desktop browser, not just mobile) but, the more functionality they have, the more likely they may be to cause problems.

If you only need the ability to quickly view mobile versions of some websites, this add-on does this basic job very well.

Enjoyed this article? Why not check out how to make Google searches in the Firefox address bar (or Search bar) search Google by name i.e. go straight to the most relevant website, instead of performing a standard Google search?

4 thoughts on “How To Display Firefox Mobile View Of Websites On A PC”

  1. Sounds like a very good idea!.

    But…. the addons MOZ site, says
    that “Go Mobile” is not compatible
    with my
    FF 16.02 browser, (under XP Pro 32 bit).
    and refuses to install it.

    What is the minimum FF version # it requires?


    • @sfdude – no idea on the minimum as I don’t keep older versions of FF but it’s ok on the current FF 18.0.2 on XP.

      Unless you have a really good reason, you should update to the latest FF18 anyway – there have been loads of security updates (as well as feature changes) since 16…

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