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".
Appname / app version indicates the application name and version. Firefoxversion will generally represent the equivalent Firefox release corresponding to the given Gecko version.
When Firefox runs on a device that has the phone form factor, there is a Mobile; token in the platform part of the UA string. The preferred way to target content to a device form factor is to use CSS Media Queries.
For increased interoperability, if the browser is running on a version below 4 it will report 4.4. Starting in Version 6, users can opt into using a GeckoView-based Focus for Android with a hidden preference: it uses a GeckoView UA string to advertise Gecko compatibility.
Klein Version (Rendering Engine) UserAgentstring 1.0 (Review)Mozilla/5.0 (Linux; Android 7.0) Apple WebKit/537.36 (HTML, like Gecko) Version/4.0 Klein/1.0 Chrome/58.0.3029.83 Mobile Safari/537.364.1+ (Review)Mozilla/5.0 (Linux; Android 7.0) Apple WebKit/537.36 (HTML, like Gecko) Version/4.0 Focus/4.1 Chrome/62.0.3029.83 Mobile Safari/537.366.0+ (GeckoView)Mozilla/5.0 (Android 7.0; Mobile; RV:62.0) Gecko/62.0 Firefox /62.0 Version 7 of Focus for iOS uses an useragentstring with the following format: Note: this user agent was retrieved from an iPhone XR simulator and may be different on device.
Some of them we have noticed are of the form Nelson; “, Reopen; “, or Open C; (note that putting space is also discouraged). Firefox OS version numberGecko version number1.0.118.01.118.11.226.01.328.01.430.02.032.02.134.02.2372.544It's easy to find the correspondences by looking at the Mercurial repository names : repositories starting by mozilla-b2g are the release repositories for Firefox OS, and have both Firefox OS and Gecko versions in their names.
The first two digits are owned by the Mozilla product team and denote versions with new features (e.g.: v1.1, 1.2, etc). The third digit is incremented with regular version tags (about every 6 weeks) for security updates, and the fourth is owned by the OEM.
Identifier preferences, (see the obsolete Sergeant Strings Reference). In the past, specific plug-ins, add-ons or extensions added user agent parts to notify sites they were installed.
The Chrome (or Chromium/Blink-based engines) useragentstring is similar to Firefox ’s. For compatibility, it adds strings like HTML, like Gecko and Safari.
The Opera browser is also based on the Blink engine, which is why it almost looks the same, but adds “Or/
This information is extremely useful to the server, as it allows serving or send back content in the most suitable format for the machine and browser you are using. Usually there is no need for this value to be tweaked as most “well-designed” websites will cater all the web browsers correctly.
Some bank websites even test for exact versions of supported browsers. It is not however a good substitute for testing with an actual instance and version of the browser.
For Mozilla Firefox, there are several add-ons available that will easily allow you to change useragentstring on the fly. Control : A highly rated plugin which is pretty simple to use.
It provides the ability to specify user agent strings on a per-domain basis. Sergeant Override : This add-on allows you to change the useragentstring from a toolbar button.
Most of the add-ons provide very similar functionality, so go with one with good rating and works best with your version of Firefox. Firefox provides a config option to change useragentstring.
If you like to use custom user agents for only certain web domains then you might be better off using one of the add-ons mentioned above or refer to the section immediately below this. It is not easy to get to change the configuration, as there is no good user interface to do this.
If for some reason you cannot or don’t want to use the about:config editor, then you can specify these values in either the pref.js or user _pref.js files. You should be able to find these files inside your Firefox profile folder.
Close the Firefox browser Using a file browser or command line, find the file named pref.js (or user _pref.js) inside the Firefox profile folder. If you just changed it for just one or two specific web domains, then there is really no good to test for it.
Do you need a quick way to change the useragentstring 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.
Once you add the extension to Firefox you can access the alternate useragentstring in two ways. Note: The useragentstring 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. The Sergeant Switcher extension provides a quick and easy way to change the useragentstring for those less than cooperative websites.
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.
An user agent is information that your browser collects from your system, and transmits to websites. It isn’t personally identifiable information so sharing it with a website is harmless.
If you aren’t familiar with the developer console, you can instead opt for an extension or add-on to change the user agent to Mac or Windows. In either case, what you essentially need is the identifier string and you can choose if you want to change it in the developer console or use an add-on.
This Chrome extension comes packed with its own quick user agent switcher which includes a Mac option. If you don’t use the useragentstring below, you can opt for the default option the extension gives you.