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 hierarchy can be navigated using a two-paned window that allows for a variety of different views on the document and all nodes within.
Inspects the structure and properties of a window and its contents.
Note: This add-on depends on binary changes to Firefox, and will not work with Firefox 2.
Available from: https://addons.mozilla.org/en-US/firefox/addon/6622
An interactive editor for XPath expressions. Choose 'View XPath' in the context menu and it will show the editor. You can edit the XPath expression and it incrementally updates the results.
Available from: https://addons.mozilla.org/en-US/firefox/addon/1095
Available from: https://addons.mozilla.org/en-US/firefox/addon/1843
Available from: https://addons.mozilla.org/en-US/firefox/addon/216
The Web Developer extension adds a menu and a toolbar with various web developer tools.
Available from: https://addons.mozilla.org/en-US/firefox/addon/60
Regular Expression Tester
Testing Tool for regular expressions with colour highlighting. The tool includes options like case sensitive, global and multi-line search, colour highlighting of found expressions and of special characters, a replacement function including back references, auto-closing, testing while writing and saving and managing of expressions.
Available from: https://addons.mozilla.org/en-US/firefox/addon/2077
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 in the status bar when browsing.
Available from: https://addons.mozilla.org/en-US/firefox/addon/249
Feature rich XPath generator, editor, inspector and simple extraction tool. Requires DOM Inspector plug-in for it to work.
Available from: https://addons.mozilla.org/en-US/firefox/addon/1192
Advanced Eyedropper, ColorPicker, Page Zoomer and other colorful goodies.
This is essentially web page DOM colour analyser that analyse DOM element colours on any Web page, find out what CSS rules set the colours, locate corresponding elements. Displays element information like tag name, class, id, size, relative mouse position etc.
Available from: https://addons.mozilla.org/en-US/firefox/addon/271
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