BlockSite is an extension, which automagically blocks websites of your choice. Additionally, this extension will disable all hyperlinks to these websites, by just displaying the link text without the clicking functionality.Warning
See report from AdGuard mentioning BlockSite: https://adguard.com/en/blog/big-star-labs-spyware.html
FocalFilter is a free productivity tool that helps you focus by temporarily blocking distracting websites. After the block timer runs out, your websites are available for you to view again.
The latest version was released August 2015. But it's still completely functional.
Block Site is a browser addon to help you block desired websites. To operate, simply right-click on any webpage and click on the "Block this website" context-menu item. The website will be added to the block list.
Sidekick is how you take back control of your most valuable resource, time. As the world gets increasingly distracted, we must be intentional with how we spend our time because once it's gone, it's gone forever.