Extension Developer's Toolbox
by Mike Kaply
9 Add-ons in this Collection
As of Firefox 33, Venkman *no longer works*, as the APIs which it needs have been removed.
Advanced Eyedropper, Color Picker, Gradient Generator and other colorful goodies...
View HTTP headers of a page and while browsing.
Draw a ruler across any webpage to check the width, height, or alignment of page elements in pixels.
Allows you to quickly switch to a different language (User Interface, Spell Checker Dictionary and Website content) in your Mozilla application.
DOM Inspector is a tool that can be used to inspect and edit the live DOM of any web document or XUL application. The DOM can be navigated using a two-paned window displaying a variety of different views on the document and all nodes within.
Developer Assistant by Ted Mielczarek, Gavin Sharp, others
A suite of tools for developers.
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