[jmisavage]

There is an add-on called uMatrix for FF. I haven't tried it so I cn't tell you if it works or not.

https://addons.mozilla.org/en-US/firefox/addon/umatrix/

[marquis-chacha]

Sorry I was unclear, uMatrix still exists, and I used to use it on Firefox, but now I get a message:

uMatrix could not be verified for use in Firefox and has been disabled.

[ajnin]

It's working for me, make sure you have the latest Firefox version, there was a bug a few days ago which broke addon-on signature verification.

[marquis-chacha]

That was it. Used to Firefox autoupdating, but didn't this time for some reason.

[yjftsjthsd-h]

Works fine here. You're on current FFx?

[marquis-chacha]

That was it. Used to Firefox autoupdating, but didn't this time for some reason.

[mxd3]

uMatrix works in Firefox stable as of last night