Hi spicermc, Both are supported by Firefox and are available as Extensions.

AdBlocker Ultimate is a Recommended extension: https://addons.mozilla.org/en-US/firefox/addon/adblocker-ultimate/?src=search

And Adblock Plus is also available: https://addons.mozilla.org/en-US/firefox/addon/adblock-plus/?src=search

The downloaded versions should work with all browsers.

Note that it is actually the opposite: extension developers should make sure that their extension works properly in current Firefox releases. Only extensions created by Mozilla are actively supported, other extensions hosted on the Addons website are third-party software and you use them at your own risk. This is also the case for recommended extensions. They are checked by reviewers on the Add-ons website, but that is where it stops. See also the License text and the Reviews of the extension to get an impression of how the extension works for others. Note that using multiple extensions for similar features like content blocking can cause issues and you always need to be aware that content blocking extensions including the builtin Firefox Content Blocking can break websites and block essential content.

How do I unblock Firefox