Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
Firebug features:
Just the way you like it
Firebug is always just a keystroke away, but it never gets in your way. You can open Firebug [...]
The Web Developer extension adds a menu and a toolbar to the browser with various web developer tools. It is designed for Firefox, Flock, Mozilla and Seamonkey, and will run on any platform that these browsers support including Windows, Mac OS X and Linux.
It is created by Chris Pederick in order to handle dozens of [...]
When browser vendors bend the standards and implement something in a different way than what the specification states, they may cause problems, or at least confusion. One example of this is the way certain browsers, the most widely used being Internet Explorer for Windows, handle alt attributes (popularly and incorrectly referred to as “alt tags”).
Alternate [...]
