All the other 'site blockers' with extra features failed to block a site.

This one does what it's asked.

simple , fast, and effective.

O Firefox bloqueou o Duolingo e não consegui desbloqueá-lo usando as sugestões do Forum de Ajuda do Mozzila. Com este Add-on, fui no ícone da barra de ferramentas, em "opções" e estava lá o bloqueio, foi só apertar no "x"zinho e tudo voltou ao normal. Top!

Obrigado por conter meus vícios.

This extension works extremely well to block ads.

It's a good add-on, I always use it. Thank you. Please add import and export domains and password to options.html

it works for me... are you guys not using it on desktop?

This site completely blocks a domain from establishing any connection to my browser. At least, the sites I blocked couldn't set any cookies when I checked with my cookie manager. I tried another block site addon and it lets set cookies. Fortunately, this one by Allen won't allow blocked domains to set any cookies. Thanks.

Non intrusive and efficient addon-on. Very satisfied, thanks :)

Very simple to use and does exactly as advertised. Thank You

good add-on. It would be nice to have a whitelist , i.e. denying a domain, but allowing certain pages or sub-structures . E.g. deny facebook.com but allow facebook.com/user/*

Great, simple addon, works as advertised. This addon actually blocked the requests to the site, like I wanted. Another addon with the exact same name just visually blocked the site but loaded it anyway - useless!