Below are the best addons I have found that help me day to day with my web development. Every developer should have these installed and you will see how much better your development will be.
Perfect addon for any developer who is trying to squeeze out better performance for your website. It profiles your pages and suggests how you can improve your website.
Pick any colour from anywhere on the page as well as having a couple of great features such as a colour palette generator and more. It is a must have for designers.
Swoosty SEO Tools
Every site needs to be SEO’d for best visibility. This tool will show you your Gooogle Page Rank, Alexa Rank as well as numerpis shortcuts to other websites which give you extensive information and allow you to view and improve the SEO capabilities of your website.
Have any other firefox tools people should know about? Post it in the comments.