The first and only download manager/accelerator built inside Firefox!
The Web Developer extension adds various web developer tools to the browser.
Xmarks is the #1 bookmarking and open tab add-on. Keep your bookmarks, and open tabs backed up and synchronized across computers and browsers. Mobile phones with Premium access. Utilize LastPass to sync passwords!
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
View HTTP headers of a page and while browsing.
FontFinder is created for designers, developers and typographers. It allows a user to analyze the font information of any element on a page, copy any piece(s) of that information to the clipboard, and perform inline replacements to test new layouts.
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)
This extension adds a new "FaviconizeTab" option to the context menu of the tab...
'lori' can tell you how long it takes to load
a page. Useful for web developers who are working on profiling, optimizing a web site.
Collections are groups of related add-ons that anyone can create and share.Explore Collections