- HTML Validator HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing.
- NoScript Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.
- Web Developer The Web Developer extension adds a menu and a toolbar with various web developer tools.
- Save Complete Saves a webpage completely, providing a better alternative to the flawed built-in save functionality of Firefox.
- FireShot FireShot is a Firefox extension that creates screenshots of web pages (entirely or just visible part).
- ColorZilla Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.