ProCon Latte is a Firefox filter that allows you to control access to inconvenient sites for children, either by offering violent content, sex, or other content for adults that may be considered inconvenient for minors.
You can activate automatic filters, that is, certain words that if present in the text of the page, will cause that site is blocked.
You can define a blacklist (Blacklist) of sites you will not be allowed access, and can also define a white list (whitelist) which is the opposite action: allow access only to sites that are added to the list.
ProCon can be password protected so that third parties can not modify the application settings and circumvent the restrictions imposed.
ProCon can be useful in schools, study centers, even workplaces, where you do not want to use the time to navigate sites that do not contribute to the tasks imposed. In these cases it may be safer to have an Internet connection through a proxy for more efficient control.
Procon 3.3 is the latest version of this add-on for Firefox that you can download free. It does not work for other browsers.