The easy way to download and convert Web videos from hundreds of YouTube-like sites.
The Web Developer extension adds various web developer tools to the browser.
Displays a country flag depicting the location of the current website's server and provides a multitude of tools such as site safety checks, whois, translation, similar sites, validation, URL shortening, and more...
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
Screengrab! saves webpages as images.
New features: upload to internet
YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.
http://yslow.org is the official open source website.
Wappalyzer is a browser extension that identifies software on websites.
Displays tabs in tiled layouts in Firefox. Arrange tiles horizontally, vertically or in a grid. Resize tiles by dragging splitter bars. Tabs and links can be dragged to open in other tiles. Supports multiple tiled layouts. Works with tab groups.
Save an image of a web page (including Flash content) to a file. Web page screenshots may be captured interactively or from the command line. Options allow you to control the output format (PNG or JPEG), image file name, scaling, and much more.
FirePHP enables you to log to your Firebug Console using a simple PHP method call.
Not using Firebug 1.9+ on Firefox 8+? See http://firephp.org/
Exports all cookies in IE manner.
Makes a Netscape standard cookies.txt file.
Very useful for WGET --load-cookies option.