Umm It's mostly a glitch with Mozilla Firefox - Trying to get many add on's / extensions to run on an interface in the browser - can be a real bastard.

There are no instructions on how to get it into the menu and or to operate it either.

Once many years and computers back, some new browser came out, and it remembered my name, my account number and the password in the URL, in it's history settings - AND ever since them I have been viciously opposed to "the LOW IQ programmers" keeping everything you do AND don't want in the browsers memory / history.

The app needs an interface that can be negaged, instead of Firefoxes idiot inteface.

I'm using this to block the DeepL and Google Translate subdomains (which would generate URLs every time I changed my input) and it works just as I hoped.

There is no regex support, and the Full URL matching mode is a bit problematic, as the URL has to be an exact match all the way down to GET parameters (?foo=1) and even the anchor (#foo) at the end. Also if you input a full URL without the protocol (e.g. https://), it may inadvertently omit the first character of the subdomain you typed.

If this add-on had regex support or a whitelist containing full URLs that the blacklist shouldn't block, I would rate this 5 stars. As it stands, any subdomain I block doesn't get suggested or auto-completed in my address bar, which is a good thing for privacy but a bit unfortunate for my use case.