Aardvark - A cool
extension for web developers and designers, allows them to view CSS
attributes, id, class by highlighting page element individually.
chromEdit - Alter the appearance of any page by editing CSS and Javascript files with this extension.
CSSMate - Firefox extension to edit CSS files.
CSS validator - Check the validity of your webpage using this CSS validator extension.
CSSViewer - See the CSS properties of page elements with this extension.
EditCSS - Play around with loaded CSS, Web Developer extension also provides this functionality.
IE Tab - Designers and developers can view their CSS projects on Internet Explorer using this extension.
Style Sheet Chooser II - Users can pick and choose alternate style sheets for a website.
FireBug - A console for debugging JavaScript, HTML, and Ajax code snippets.
HTML Validator - Cool extension to validate web pages with HTML standards of W3C.
JavaScript Debugger - JavaScript debugging extension enables a strong debugging environment.