A2 Codesigner

I have found all of these add ons very useful for developing web sites and inspecting other developers web sites. I am also assuming that all the new web developers out there already have Firefox, if your using Internet Explorer for anything other than testing, you still have a lot to learn.

1. Firebug

Edit, debug, and monitor CSS, HTML, and JavaScript live in any web page. If you only get one of these add ons make it this one.

2. Web Developer

Along with Firebug this tool box has everything you need to inspect and edit code on any website.

3. YSlow

Optimize the performance and download time of your websites with this tool.

4. Accessibility Extension

Support web developers and people with disabilities in accessing and testing web resources for accessibility features.

5. Operator

Operator leverages microformats and other semantic data that are already available on many web pages to provide new ways to interact with web services.

Search the full list of Firefox Add Ons.