Firebug: a JavaScript, CSS, HTML and AJAX debugger

If you need a comprehensive JavaScript, CSS, HTML and AJAX debugger then you should have a look at Firebug. Firebug is a Firefox extension that “lets you explore the far corners of the DOM by keyboard or mouse. All of the tools you need to poke, prod, and monitor your JavaScript, CSS, HTML and Ajax are brought together into one seamless experience, including a debugger, error console, command line, and a variety of fun inspectors.

Firebug 0.4 was just released yesterday by the author Joe Hewitt.

I have had my problems debugging AJAX so hopefully Firebug can come to the rescue here.