LeechBlock is a simple free productivity tool: an extension for the Firefox web browser designed to block those time-wasting sites that can suck the life out of your working day. (You know: the ones that rhyme with “Blue Cube”, “Space Hook”, “Sticky Media”, “Quitter”, and the like.) All you need to do is specify which sites to block and when to block them.

You can specify up to six sets of sites to block, with different times and days for each set. You can block sites within fixed time periods (e.g., between 9am and 5pm), after a time limit (e.g., 10 minutes in every hour), or with a combination of time periods and time limit (e.g., 10 minutes in every hour between 9am and 5pm). With the lockdown feature, you can block sites immediately for a specified duration. You can also set a password or random access code for LeechBlock’s options, just to slow you down in moments of weakness!

The sites to block can be specified using wildcards (e.g., *.somesite.com) and exceptions (e.g., +allowme.somesite.com).

LeechBlock also keeps track of the total amount of time you have spent browsing the sites in each block set.

LeechBlock was inspired by Gina Trapani’s Invisibility Cloak user script for the Greasemonkey extension.

Important note #1: LeechBlock is not designed for parental control or for blocking offensive content. You are advised not to try to use it for these purposes.

Important note #2: Although LeechBlock prevents you from browsing sites (at the specified times) it may still allow your Firefox browser to briefly connect to those sites (so that, e.g., your IP address may still be logged by the blocked site). If you want to prevent any such connection, you should use some lower-level blocking method (e.g., install and configure a HOSTS file manager like HostsMan).

The password feature isn’t intended for security purposes, only to make it more difficult to bypass the blocking in hasteā€”to delay you just long enough for your reason/conscience to wrest back control from your baser instincts! So a lengthy but memorable password will be most effective. Alternatively, try one of the random access code options.

Note that by default the time spent on a site is calculated by summing the time that pages from the site have focus in the browser, rather than the time that those pages are loaded in the browser. (You can change this default behavior via the options.)