'Classic Toolbar Buttons' add-on restores old toolbar button ui (known from Fx 4-7s small view, Fx 4-12s large view & Tb 5-14) for current Firefox, Thunderbird and Seamonkey versions on Windows.
Beta builds on versions page!
Color tools for web development.
Color picker and eyedropper + saving colors and trying out colors with drag and drop.
Tweak Network will speed up the loading of web pages and increase the maximum number of simultaneous downloads from a site.
Automatically resumes YouTube videos from where you played them last. Without this extension, for example, when you click through YouTube videos, back and forth, they always start from the beginning.
Provides user with tab related stats and memory usage
The extension previously known as GooglePreview. Inserts preview images (thumbnails) and popularity ranks of web sites into the Google, Yahoo, Bing and DuckDuckGo search results pages.
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 is for those TB3 users who want the multiple-columns view that TB2 allowed
Allows you to quickly switch to a different language (User Interface, Spell Checker Dictionary and Website content) in your Mozilla application.
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/
Adds an about:addons-memory page that details add-on memory usage
Firefox Interest Dashboard provides a colorful and interactive view of your interests based on your browsing history.
Bring your bookmarks into view with just a gesture. Move the sidebar across the screen. Open a different sidebar by just clicking its title. And more! Keeps your sidebar simple and quick to access!