Pluckeye is a filter designed with compulsive users of porn in mind.

When Pluckeye is first installed, all images on the Internet are blocked.

The user then typically whitelists sites from which images are allowed, and
sets a waiting period that prevents the user from adding new rules and
accessing additional images before the waiting period has expired.

Pluckeye supports scheduled access, accountability, and a few other features.

It is primarily for the person hoping to quit porn, but it is also used by
people who simply want to limit their own access to sites such as gmail or
facebook and to avoid clickbait.