I can't get it to work in Firefox 129.0. Also, I'm missing a hint, whether the regex-matches get excluded from CORS (then the default setting would be very dangerous), or included? And what when the button is set to disabled? Is the URL list in charge then? Or is it in charge, when enabled? And, do I have to match my local domain oder the remote?
So, in all, seems like a nice plugin, if it were working, and if it was more clear about what the settings mean.

Works but not so friendly interface.
Make sure to ADD and SAFE the URL.
If you make a request from e.g. localhost to someServer you have to add the URL of someServer.

Took me some 20min to figure out since it is unclear from the user interface.

Doesn't work in Firefox 124. No changes are saved or applied.

don't work

Does not work, even enabling in the UI is not saved.

It doesn't work. I failed to get my regex saved.

Works well. Simple and clearer to configure than other CORS plugins.

Well, no problem, it works, at least for now.
The UI is also more friendly than others.

Worked fine, until I updated 14.3.2020 my Firefox to 74.0 version. It stop working.

*edit
Ok, this addon works but however, doesn't work on files. You need open page with URL domain, not from hard disk as file.

After installing the addon on FF Quantum 60.9.0esr 32bit, youtube video won't play anymore. Uninstalling the addon makes youtube play normally.

Works nicely and with a friendly interface.
It's a shame that those ancient reviews from when the plugin failed after an API change still downrate this tool...

It just doesn't work, FF still blocks request even with wildcard CORS header.

Does not work with Firefox Developer Edition (65.0b8 (64-Bit)) and latest macOS update (10.14.2)

Add-on works great on Firefox running under Windows on my PC. It seems not to work on Firefox running under Android on a Tablet ("+/x"-Button not shown). Is there a way to activate it under Android?

does not work on mac osx using firefox 59.0.2 (64-bit)

does not work