It's available as an add-on. You can find it by searching in the add-ons manager (cmd+shift+A in osx). This brings you to https://addons.mozilla.org/en-US/firef

It's available as an add-on. You can find it by searching in the add-ons manager (cmd+shift+A in osx). This brings you to https://addons.mozilla.org/en-US/firefox/addon/ublock-origin https://addons.mozilla.org/en-US/firefox/addon/ublock-origin where you can click to install. I recommend searching for it on your own through the built-in mechanism rather than trusting a link provided by a stranger.