Betterfocus

Betterfocus is a Firefox extension that helps to curb Internet addiction by
hindering access to websites. When the extension is turned on, it will prevent users from
opening websites without providing confirmation first. This offers users a chance to rethink
whether it is necessary for them to continue to a website. This extension was written in
Javascript.

You can find and install this Betterfocus at https://addons.mozilla.org/en-US/firefox/addon/betterfocus/.