The User Agent Switcher extension adds a menu and a toolbar button to switch the user agent of a browser.
The Web Developer extension adds various web developer tools to the browser.
FireShot Webpage Screenshots captures pages entirely. Demo: http://bit.ly/RlBQMV
The screenshot can be quickly captured and:
― Saved as Image or PDF
― Sent to clipboard
― Annotated *
― Uploaded *
― E-Mailed *
* OS Windows only
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
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.
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
For Firefox 23+, you need 0.958 (under review)
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/
CodeBurner is a Firefox add-on that integrates with Firebug, to extend it with reference material for HTML and CSS.
Finds HTML elements matching chosen CSS selector(s) or XPath expression
Quickly test out your web pages in Internet Explorer, Chrome, Safari, or Opera. Open With opens the current page in your other browsers with just one click. Add Open With to your menus, toolbars and developer toolbox today!
Collections are groups of related add-ons that anyone can create and share.Explore Collections