This blocker is simple and great to use. It's UI is more simplified. This blocker blocking all the sites which one needs to block. This app has improved.
When you right click to block site then it's actually blocked but to see effect you have to close the tab. You can also block manually in it's settings page.

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/*