The latest major version of Firefox has just been launched and to celebrate (and try and get into the Guinness Book of World Records), yesterday was download day.

I don’t know about other platforms, but I can tell you my story of love and hate with Firefox on the Mac: Firefox 2 has always been on my computer, even though I was using Safari for its speed, stability and OS integration. Now I’m going back: Firefox 3 is a lot faster and stable, not to mention I can go back to using proper keyboard shortcuts (something Safari lacks, particularly for tab controls).

Being a web developer, the browser is a key tool in the work I do every day. Along with Firefox 3, there are a bunch of useful extensions you can install to work on the web. The next few paragraphs highlight some of those.

Tools of the trade

- Firebug is a swiss-army knife that allows you to: inspect specific nodes on a page, change the code and css of the page on the fly, test Javascript code in a console and see network debug information for each request. Get Firebug from the project’s page. (I’m using the 1.2 beta and loving it).

- Yahoo!’s YSlow relies on Firebug and highlights potential problems with your page, app or service, as well as tips on how to solve them. If you’ve read “Building scalable websites”, this is the tool that goes with the book. Learn more about the project and download it here.

- Live HTTP Headers let’s you see the headers exchanged between your browser and the web server for each request on a given session (i.e.: html, images, CSS files, etc…). Get it here

- Tamper data is what you need if you want to mess around forms after being submitted but just before being POSTed to the server. Give it a spin if you’re into tampering your requests.

- Web Developer used to be the de facto extension when developing for the web. It has been replaced with Firebug’s features but if all that you want is outline certain elements or resize the window, this may still be the right tool for you. You can download it here.