The LeechBlock Firefox and Chrome productivity tool extension prevents you from browsing certain sites or social media while working. You fill in up to six sites you want to avoid and when you want to avoid them (day and time), and that’s it. Job done. It’s simple to install, but you will need to put aside some time to fill in your preferences (you’ll find plenty of easy-to-follow examples on the site). You can use wildcards, too. Basically, this little tool does exactly what it says on the packet. Oh, and it’s free!