This extension will block access to websites of your choosing. A master password controls all customization options, as well as access to any blocked site. It's also possible to redirect navigation from one specific website to another. 

FAQs Page:
https://add0n.com/block-site.html

Features:
1. Block unwanted domains. 
2. Prevent access to a range of websites using wildcard matching or regular expression matching.
3. Reverse mode allows access to only some hostnames and blocks access to all others. 
4. Custom redirection; you can redirect a single blocked hostname to a new destination. 
5. Display a custom message on blocked pages.
6. Time and date based blocking. Only block access to the websites at specified times and dates. This feature can be configured per hostname. 
7. Protect data leakage. This extension prevents certain hostnames from gathering network activity from your computer, since blocking occurs before any network request is emitted to the server.
8. Auto-closes blocked tabs after a period of time.
10. Closes annoying pop-ups as soon as the opening request is received.
11. Pause and resume blocking from the right-click context menu of the toolbar button.
12. Supports overwriting configurations by managed storage

For the FAQs and general feature suggestions please use:
https://add0n.com/block-site.html

For technical bug reports use:
https://github.com/ray-lothian/Block-Site/issues