The Blacklist tool enables you to enter domain names which should be blocked. When your web browser tries to request any page from a blacklisted domain name it is blocked. You can also enter wildcards to block subdomains.

Blacklisting is useful when you’re testing a site that loads resources, such as images, from another server. Blocking those requests enables you to determine the size and speed of the site without them. Particularly useful if you’re developing a site with banner ads and don’t want to brainwash yourself while you work.