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".
You can change it via Developer Tools menu which you can access by clicking the three-dot icon in the top-right corner of Microsoft Edge. In the early days of the internet, websites didn’t care what browser you used, because most pages were static.
But today’s dynamic websites often adapt to the operating system, browser, or screen size your device uses. An user agent is a string (line of text) that your browser sends to websites when you access them.
User agents are important because sites can use them to modify the content they send to your browser. For example, if you visit most modern sites in Internet Explorer 6, you’ll see a message that you need to upgrade your browser for proper compatibility.
User agents also come into play when browsing on a mobile device, so websites know to show you the mobile-friendly version of a page. Open Chrome’s Developer Tools by right-clicking anywhere and choosing To inspect, hitting Ctrl + Shift + I, or by pressing F12.
On the Network conditions tab, uncheck Select automatically and you can then choose a new user agent from the list. Note that this setting will revert to normal when you close the developer panel, and only applies to your current tab.
You can also change Browser profile from Desktop to Windows Phone to view the mobile version of webpages. You’ll need to enable the hidden Develop menu in Safari before you can change your user agent.
While there’s no quick toggle to change your user agent in the mobile versions of Chrome and Safari, you can easily make websites think your phone is a computer. On Safari for iOS, tap the AA button to the left of the address bar and choose Request Desktop Website.
You’ll find the same option in Chrome for iPhone by tapping the Share button at the top-right, followed by scrolling down and choosing Request Desktop Site. While swapping your agent can’t accommodate every possible real-world situation, it lets you get some basic testing done in a fraction of the time.
Further, if backward compatibility is important for your site, swapping your user agent to IE 8 is a lot easier than installing a copy of ancient browsers manually. Browsing mobile versions of pages means you only get the basics and aren’t wasting data on multimedia or other large items.
While not as common as it once was, sometimes you’ll come across websites that tell you Firefox doesn’t work with the page, or you must use Internet Explorer, or other similar warnings. Some people explain that they use these services to get around sites that block entire operating systems.
While there’s really no good reason for a site to block an entire OS, you could run into a page that complains about you using Linux. If you’ve used Windows all your life, you can jump around some sites and see if they look any different when using Mac or Linux.
Or change your user agent to an ancient version of Internet Explorer, then see how many sites still support it. Some browser-switching agents even allow you to pose as Google bot, the robot Google uses to crawl and index the web.
Changing the user agent string can be useful in certain scenarios when some website's functionality is locked down to the specific platform and you need to bypass the restriction. This allows developers to differentiate various device classes like tablets, phones, Desktop PCs and laptops, and more.
The user agent string can provide web servers some details about the user's operating system, and the browser version. For example, the download page on Microsoft's website checks the user agent of the browser.
If it reports the Windows operating system, the Media Creation Tool will be offered for download. However, if the user agent reports Linux, Android or iOS, you will see direct download links to ISO files.
Choose the desired web browser to change the user agent string. The list includes various versions of Internet Explorer, along with Opera, Safari, Firefox, and Chrome.
Using the built-in Developer Tools option, you can change the user agent in Microsoft Edge any time. When you load a web page such as groovyPost.com, a list of checks are performed to determine the platform (macOS, Windows, Linux), web browser (Microsoft Edge, Chrome or Safari for iOS) and the system type (x86 PC, Galaxy Tab, iPhone/iPad).
You likely see the difference when you load our website in Microsoft Edge on a Windows 10 PC vs Chrome on an Android smartphone. A feature of web browsers called the user agent string makes this happen.
Select the Emulation tab then click in the User agent string list box. Both Edge and Internet Explorer support a variety of modes, including Opera, Safari, Firefox, and Chrome.
When selected, the page you are browsing will be refreshed in real time, letting you see how it behaves in that particular web browser. Click in the Custom list box then choose the desired browser mode.
Opera’s Developer Tools are based on Chrome, but accessing it is a bit easier. Unlike Chrome, Opera, Edge, and IE, Firefox doesn’t have a user -friendly way to quickly switch the user agent string.
There are add-ons with similar names, so, look for the version with the globe icon and a network pipe attached. Choose the desktop web browser and operating system platform to view the desired website.
This feature is useful for SEO professionals, for example, to identify issues with cloaking which is against Google’s Webmaster Guidelines or auditing websites which has different look depending on the device. User agent is an HTTP request header string identifying browser, application, operating system which connects to the server.
Get our daily newsletter from SEJ's Founder Loren Baker about the latest news in the industry! The new Microsoft Edge running on Chromium isn’t yet here officially, but a leaked build allows us to try out the browser in anticipation of its highly-anticipated release.
Using the browser on a daily basis isn’t obviously recommended as experimental builds like this can’t by any means become your main driver. For many users, switching to a different user agent and thus emulating another browser is a method to bypass certain website restrictions that concern a specific app.
For example, if a website doesn’t support Chromium, you can very well change the user agent to mimic a different browser like Mozilla Firefox. The best example is Skype for Web, which doesn’t work in Firefox anymore, so Mozilla users need to switch to another user agent to connect to the service.
For those unfamiliar with this screen, it’s specifically supposed to provide developers with advanced tools that let them analyze code and website performance. Changing the user agent is actually considered a developer option that helps webmasters check their pages against potential compatibility issues with different browsers.
There are more than 100 predefined user agent strings available to choose in the Add-on options page. This list covers all modern browsers including Google Chrome, Mozilla Firefox, Opera, Safari, Marathon, as well as Mozilla Thunderbird browser and many more.
Also, all the user agents are provided for both desktop and mobile platforms. Each UA can also be modified from add-ons options page to match your specific need.
Custom Sergeant String (abbreviated as Cuts) is a browser add-on (extension) that enables you to quickly change the user agent (UA) of your browser to your desired value. Once you install the add-on, please go to the options page to start working with this extension.
How do I work with Custom Sergeant String add-on? In order to find an user agent, as mentioned above, you can use the predefined UA table and choose a string from there.
There are more than 100 UAS available in the table for almost all modern browsers and ranging from desktop to mobile platforms. There are plenty of websites to offer free user agent string lists.