The web developer extension adds a toolbar to iceweasel/firefox with numerous features aimed at web developers. there are buttons to disable various browser features (java, javascript, images), to view, edit, and disable stylesheets, to manipulate web forms, to view the topography of a page, to display tag details, to view the headers of a request, to clear the cache, cookies, and history, to view comments, to zoom, to outline selected classes of tags, to resize the browser to match a target resolution, and more. there are also buttons for easy access to the page's source, to many web validation services, and to important web standards documents.