52 Add-ons in this Collection
Adds an about:addons-memory page that details add-on memory usage
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.
This wizard creates an XPI that rebrands Firefox, SeaMonkey or Thunderbird. You can change the brand name as well as the brand images and icons.
Pretty-prints JSON content in the browser for easy, unobtrusive viewing.
Install Browser Extensions straight from GitHub Repositories
Markdown document viewer.
Allows to visualize formatted markdown documents in browser.
Developer Assistant by Ted Mielczarek, Gavin Sharp, others
A suite of tools for developers.
Easiest way to Add and Manage Custom User Styles in Firefox.
Add, Edit, enable, disable and delete in-numerous User Style Sheets to redesign the Firefox and the Web.
Foundstone HTML5 Local Storage Explorer allows for viewing, modifying and deleting of data items stored in the browser's LocalStorage. LocalStorage is a client side storage technology introduced in HTML5.
A quick restartless magnifier to debug styles and web pages.