A user agent is a computer program representing a person, for example, a browser in a Web context.
Besides a browser, a user agent could be a bot scraping webpages, a download manager, or another app accessing the Web. Along with each request they make to the server, browsers include a self-identifying User-Agent HTTP header called a user agent (UA) string. This string often identifies the browser, its version number, and its host operating system.
Spam bots, download managers, and some browsers often send a fake UA string to announce themselves as a different client. This is known as user agent spoofing.
A typical user agent string looks like this: "Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:35.0) Gecko/20100101 Firefox/35.0".
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 Sergeant Switcher extension.
Before adding the extension to our browser we tested the user agent string at UserAgentString.com and got a positive I.D. Once you add the extension to Firefox you can access the alternate user agent string in two ways.
Note: The user agent string will automatically reset back to the default each time you restart Firefox. You can create, edit, and delete current user agent strings or use the import/export functions.
For those wanting to add additional user agent strings visit this website (available in XML file format). She has previously written under the pen name “Asian Angel” and was a Life hacker intern before joining How-To Geek/Lifesaver Media.
User agent is an HTTP request header string identifying browser, application, operating system which connects to the server. Not only browsers have user agent but also bots, search engines crawlers such as Google bot, Google AdSense etc.
It allows sites to determine specific details, which in turn alters how the page is served to the user. For instance, menus will be easier to touch and read, and text will be more stripped down and readable.
Normally, users are oblivious to the exchange of browser user agent data; there are, however, ways in which users and developers can change the user agent to test for different platforms or simply to mask their browser ID. Browsers have a fingerprint that can help uniquely identify users with the user agent being one of these factors.
When using Edge, open a page and press the F12 key to access the developer settings. Select the “Emulation” tab and look for the Sergeant string list.” Here you can choose to make Edge mimic the browser of your choice.
Just as with Edge, Chrome has an useragentchange within the developer settings, although it is a lot more complicated to access. From there click “Tools” and then “Developer Options.” You can also easily access this via the key combination of Ctrl + Shift + I.
As you can see below, there will be an option to change the user agent by unpicking the “Select automatically” box. A warning will appear, but it is quite safe to proceed, providing you don’t change settings or flags without due care and attention.
If you don’t fancy the idea of messing with a browser’s settings, then there are some add-ons and extensions that will do the job for you. It is currently, at the time of writing this article, a featured extension from Firefox, so that may put to rest some concerns that users may have.
Matthew Muller Matt has worked in the tech industry for many years and is now a freelance writer. An user agent tells websites what type of browser and operating system you're using.
This information helps the web server deliver content that's compatible with your browser. If websites tell you that your browser is outdated or incompatible even though Firefox is up to date, an incorrect user agent may be the cause.
This article explains how to fix problems with your Firefoxuseragent so that websites work properly. You can changeFirefox's user agent to trick websites into thinking that you're using a different browser or operating system.
Websites may not display correctly or may show a message that your browser is outdated or incompatible, based on the detected user agent. It's important to switch Firefox back to the default user agent so that websites work properly.
The Application Basics section will show your current Firefox version and will include a Sergeant entry. You can open the Properties of the Firefox desktop shortcut from the right-click context menu.
Type about:config in the address bar and press Enter Return. Right-click Hold down the control key while you click on each of these preferences, if they exist, and select from the context menu.
Type about:config in the address bar and press Enter Return. See Configuration Editor for Firefox for more information about using the about:config page to reset or delete preferences.
After resetting your user agent, you may need to restart Firefox and clear your cookies and cache: If you ever wanted to make your web traffic seem like it was coming from a different browser–say, to trick a site that claims it’s incompatible with yours–you can.
If you don’t see the console at the bottom, click the menu button in the top right corner of the Developer Tools pane–that’s the button just to the left of the “x”–and select “Show Console”. On the Network conditions tab, uncheck “Select automatically” next to User agent.
It only works while you have the Developer Tools pane open, and it only applies to the current tab. To create the preference, right-click on the about:config page, point to New, and select String.
This setting applies to every open tab and persists until you change it, even if you close and reopen Firefox. To revert Firefox to the default user agent, right-click the “general.user agent.override” preference and select Reset.
Microsoft Edge and Internet Explorer have user agent switchers in their developer tools, and they’re nearly identical. To open them, click the settings menu and select “F12 Developer Tools” or just press F12 on your keyboard.
The developer tools will open in a separate pane at the bottom of the window. You can find extensive lists of user agents on various websites, such as this one.
It only applies to the current tab, and only while the F12 Developer Tools pane is open. Chris has written for The New York Times, been interviewed as a technology expert on TV stations like Miami's NBC 6, and had his work covered by news outlets like the BBC.
Since 2011, Chris has written over 2,000 articles that have been read more than 500 million times---and that's just here at How-To Geek.