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Leonora Tindall 2017/11/08

RandomUA Logo

Install for Firefox or Chrome, or view on GitHub

What is RandomUA?

RandomUA is a WebExtension that changes your User-Agent string to a sensible-looking, desktop-browser-like UA string which is different for every request.

A User-Agent string is a piece of information that your computer sends to every website you go to. It tells them what software you use to access the Internet, what kind of computer you’re using, and what kind of operating system you use. Some of this is really important to those websites, but most of it isn’t, and it can be used to help track you without your consent.

Many browser fingerprinting solutions use the User-Agent as a relatively constant string, because most users UAs only change when their browser updates. Therefore, having a different UA on each request make it a lot easier to evade these tracking schemes.

Sample UA Strings

Mozilla/5.0 (Windows NT 5.64; rv:193.0) (KHTML, like Gecko)  AppleWebKit/193.0;
Mozilla/5.0 (Windows NT 7.59; rv:869.0) Gecko/20100101  Chrome/531.0 Firefox/869.0;
Mozilla/5.0 (Linux i686 on x86_64; rv:514.0) Gecko/20100101 Mobile Chrome/514.0;
Mozilla/5.0 (Windows NT 9.81; rv:77.0) Gecko/20100101  Chrome/77.0;

These generated UAs preserve important markers (like the Mozilla/5.0 and Gecko or like Gecko compat markers, and the Mobile flag) so that your browser isn’t served unusable content, but randomizes parameters that websites really shouldn’t care about (like OS version, browser version, and processor architecture) to protect your privacy.


RandomUA requires access to all URLs and web request data for its core function: it has to be able to change your user agent string!

Other Platforms

Simply run the included script and install the generated XPI file.


Contributions are welcome, either as PRs or issue reports. Please use GitHub issues for both bugs and feature requests.