Recently, Mozilla conducted an experiment to check whether the user agent in Firefox/100.0 breaks the website.
The User-Agent (UA) string commonly used by browsers helps in determining which browser is being used by the client, the version of the browser, and the operating system on which it is running.
On the release of each new browser version, the developers likewise advance the user agent string version.
Let’s see an example to check whether the browser version matches the User-Agent version.
Below, we have taken an example for the current user agent for Mozilla Firefox version 90
Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:90.0) Gecko/20100101 Firefox/90.0
However, please take a note that in case you have the Firefox ‘privacy.resistFingerprinting’ setting set to ‘True,’ your user agent version won’t be the same as the browser version it will be locked to ‘Firefox/78.0.’
Similarly, for Google Chrome 92, the current user agent is:
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/92.0.4515.131 Safari/537.36
Now, let’s understand how user agent works:
On the first request from the user, the user agent file containing software info, name, technology, and version is sent to the website so that the website can offer a customized response that will be different for different browsers.
How to test if upcoming user-agent, Firefox 100 UA breaks sites?
If you wish to experiment with the forthcoming user agent, you can do so by altering the user agent string:
- Open your Firefox browser, then type in about:config in address bar.
- Go to search bar and type general.useragent.override to search.
- Choose the ‘string’ as data type and then click (+) to open up a field.
- Once you click the (+) sign, a field will be opened where you need to add the beneath text:
- Mozilla/5.0 (Windows NT 10.0; rv:100.0) Gecko/20100101 Firefox/100.0
- Next, tickmark the setting to store your changes.
- Now, as your changes have been saved, you can close the about:config tab
On applying this change, if you observe any issues with websites, report the bug to Mozilla.
Additionally, if you want to revert back to the default string, follow steps 1 and 2 to delete the configured setting.
Featured Image by: mozilla.org/en-US/firefox/