Simple UserAgent Spoofing автор Vidcass

This extension is meant to be used on Firefox-ESR running on Debian Stable. For a couple reasons, you may want your browser to appear to be something else. This requires changing the user-agent. The best way to do this if you have low trust, is manually yourself following the directions here: https://www.whatismybrowser.com/guides/how-to-change-your-user-agent/firefox

This extension defaults to a modern windows/edge user agent. You can supply your own using the extension icon. If you press clear it will return to the default. To turn it off just disable the extension in your extension manager.

The permissions for this extension look scary, because it has to listen to communication between your browser and the target site in order to replace any request for the user-agent with the one that you specify in this extension. You can see the source code for this extension at the home page link on the left. The filters tells you what is being listened for.

It also listens for and blocks some additional requests that can be used to detect
when browsers are lying about themselves via the user-agent.
https://developers.whatismybrowser.com/learn/browser-detection/client-hints/detect-windows-11-client-hints

If you have suggestions for improving this extension, especially in a way that minimizes the permissions required to do the job, please let me know.