It doesn't work.

This doesn't work. I have to manually change the user agent on every startup or time interval. I don't need a data thieving, resource wasting, pretend add-on for that. There is a "Random User-Agent (Switcher)" that works perfectly and is very simple to set up.

cloudflare captcha + youtube are broken with

Please update latest user agent on -UserAegntSwither

It works, but apparently, it completely breaks Cloudflare's verification captcha system, so I can't use it.

turns out this extension is injecting scripts into pages, and breaks all cloudflare protected sites

Unfortunately I have discovered that the current version of this add-on triggers the Cloudflare 'Captcha of Death' denying access to hundreds of web-sites and as such I have deactivated it.

works great, so many populated presets already

Literal god-send. On Linux trying to get Windows .iso files for VM and because I'm on a desktop computer Microsoft in it's infinite need to control users does not allow the download of .iso files or even make it an option... unless you change the user-agent of course, then it's not a problem any longer. Saved me having to actually use my phone to do it again like last time. Nice work people!

Super confusing interface. Choosing different user agents causes them to be smooshed onto the default user agent. Doesn't appear to actually work consistently at all.

It was last updated 2 years ago; looks like abandonware.

didnt work with cloudflare servers

Whitelist and blacklist modes are confusing, because the user can't see what agent strings are related (used or not used) to these modes.
Custom mode is not user friendly.
However it seems to be doing the job well... if you ever can figure out how to do it...

where is [Apply only this 'website.com' ] ??

not every one wants to use container??

so unusable....

you couldn't have made it any more confusing. i have no idea how to use this shit. this is so sad, i wish user interfaces were real.