1. firebug

I dont think i need to explain the importance of this plugin. It’s the best thing since the invention of sliced bread.

2. firecookie

This one works in conjunction with firebug. It allows you to edit cookie values. Especially useful when you need to reset a cookie based login logic. Just find the session cookie name and delete it. You can have a brand new session. Also good for poking around and seeing the inner workings of websites.

3. pixel perfect

Also works in conjuction with firebug.

The site doesn’t come out quite as  exactly as the psd? And you can’t quite tell what is off. Well, with pixel perfect, you can add an image overlay of you psd design to you browser, so you can line up the design with the html version to see what is wrong exactly.

4. measureit

Not sure how many pixel a particular area takes up? MeasureIt can help you measure the area in pixels. It might be hard to find for first timers. It’s all the way on the lower left hand corner.

5. SenSEO

Also works in conjuction with firebug.

SenSEO tells you exactly how and what you site is lacking in SEO aspect. Just type in the keywords.

6. Javascript debugger

If you find the javascript debugger that comes with firebug lacking somehow, you can install this one.

7. Tamper Data

Use tamperdata to view and modify HTTP/HTTPS headers and post parameters

8 Yslow

Also works in conjuction with firebug.

Is your site running slow? Use this to find out why.