Greasemonkey

Allows users to alter webpages using small pieces of javascript.

User warning: not all greasemonkey scripts are free software so the user needs to be wary. Read The JavaScript Trap for more information.

Customize the way a web page displays or behaves, by using small bits of JavaScript.

Allows you to customize the way a web page displays or behaves, by using small bits of JavaScript.

Hundreds of scripts, for a wide variety of popular sites, are already available at http://userscripts-mirror.org.

You can write your own scripts, too. Check out http://wiki.greasespot.net/ to get started.

Having trouble? Please don't post comments here, nobody will see them. If you need help, please read:
http://wiki.greasespot.net/Greasemonkey_Manual:Getting_Help