If you are a web developer you need this extension. I thought Firefox as a development tool just couldn’t get any better, but in Firebug 1.0 I think we have an extension which would give the mighty Web Developer Toolbar a serious run for its money in terms of ‘which is the most helpful extension available to developers’. Put Web Developer Toolbar and Firebug 1.0 together, and you have an unbeatable and essential toolset for getting modern websites built and tested.
Firebug has been around in 0.4 or less form for quite a while, and it’s proved itself a useful little tool, offering a good way to drill into the beating heart of the page you’re visiting and extracting various bits of information about it. Firebug 1.0 was recently released as a beta and it’s a leap, a sprint, and a quick rally drive ahead of the game.
It’s pointless me repeating what this extension can do for you as a web developer, when the homepage says it all so well. Rather, I urge you to go get it and spend ten minutes playing with it, discovering all the funky stuff it does.