Strict Workflow is a Chrome add-on that will help you stay more productive at work by temporarily blocking social and other time wasting websites.
Unlike the .hosts file technique that completely blocks websites on your computer, Strict Workflow is a little more lenient.
It blocks the sites for 25 minutes allowing you to work distraction-free and then removes the block for 5 minutes. You can repeat until all your work is done. A count-down timer in the Chrome toolbar displays the time left in your current session.
The extension automatically blocks the most popular distracting sites – like Twitter, Facebook, Reddit, etc. – by default but you can easily customize this blacklist.