LeechBlock is the best extension I've used for this purpose. I don't think I would have gotten my degree if it wasn't for LeechBlock preventing distractions :)

LeechBlock NG is a very good add-on! It does exactly as advertised.

A very nice redirect URL for your leeches would be "https://en.wikipedia.org/wiki/Special:Random", so you actually learn something worthwhile when looking for a distraction ;)

works as expected. thanks to all the open source community who contributed to this project and the developers of this extension.

It is wonderful. I find that this program avoids me wasting time on social media sites.

Does its job really well and is pretty easy to setup as well as activate.

Welcome

It's just the beginning of an amazing journey and adventure

The app works fantastically. I really give use of the "Lockdown" option for long periods of time, so far it helped me to spend less time on social media.

It is impressive. I use it to block adult sites and it works perfectly. Just add few matching keywords and boom. It works all the time.

Works as advertised. easy to set up and blocking reliably

Simple and effective. Free as in beer. Preferred alternative to paid ones.