Web development

I've prepared the list of useful extensions for FireFox browser. These extensions are very useful for web developer.
My favorite extension is "Web Developer" and "Live HTTP Headers" on bottom of below list.

Add N Edit Cookies
http://addneditcookies.mozdev.org/installation.html

Live HTTP Headers
http://livehttpheaders.mozdev.org/installation.html

QuickJava
https://addons.mozilla.org/firefox/1237/

TamperData
http://tamperdata.mozdev.org/installation.html

FireBug
https://addons.mozilla.org/firefox/1843/

Download Statusbar
https://addons.mozilla.org/firefox/26/

Web Developer
https://addons.mozilla.org/firefox/60/