Firefox has some cool add-ons which make the job of website designers much easier. These add-ons are definitely going to improve your work-flow and enhance your overall internet browsing experience. Don’t miss this chance to work quicker and better!
Firebug
Firebug integrates with Firefox to put a wealth of development tools at your fingertips while you browse. You can edit, debug, and monitor CSS, HTML, and JavaScript live in any web page.
http://addons.mozilla.org/en-US/firefox/addon/1843
Web Developer
The Web Developer extension adds a menu and a toolbar with various web developer tools.
http://addons.mozilla.org/en-US/firefox/addon/60
ColorZilla
Advanced Eyedropper, Color Picker, Palette Viewer and other colorful goodies for your Firefox.
https://addons.mozilla.org/en-US/firefox/addon/271
FireShot
FireShot is an advanced screen capture add-on for Firefox. In addition to giving you the ability to capture an entire web page, FireShot also allows you to add add graphics and notes directly to your screen captures.
http://addons.mozilla.org/en-US/firefox/addon/5648
Codetech
Get the feel of Dreamweaver in a Firefox extension. Edit your documents right next to your web pages as you surf.
https://addons.mozilla.org/en-US/firefox/addon/1002
CSS Validator
Validates a page using the W3C CSS Validator.
http://addons.mozilla.org/en-US/firefox/addon/2289
HTML Validator
HTML Validator is a Mozilla extension that adds HTML validation inside Firefox and Mozilla. The number of errors of a HTML page is seen on the form of an icon in the status bar when browsing.
https://addons.mozilla.org/en-US/firefox/addon/249
W3C Offline Page validator
Validates the source of a HTML/XHTML page via the W3C Markup Validation Service using the direct-input form.
https://addons.mozilla.org/en-US/firefox/addon/6006
Greasemonkey
Allows you to customize the way a webpage displays using small bits of JavaScript.
https://addons.mozilla.org/en-US/firefox/addon/748
GridFox
Draws a grid on top of a website. This is useful for checking designs that are supposed to follow a grid-based layout.
https://addons.mozilla.org/en-US/firefox/addon/4904
HttpFox
HttpFox monitors and analyzes all incoming and outgoing HTTP traffic between the browser and the web servers.
https://addons.mozilla.org/en-US/firefox/addon/6647
CSSViewer
A simple CSS property viewer.
http://addons.mozilla.org/en-US/firefox/addon/2104
IE NetRenderer
If you are like me and design your sites for Firefox then this is a great tool for you. IE NetRenderer will create you an image of how the website looks in IE 5.5, 6, 7 and 8 so you can get an idea of whether or not it looks right in IE.
http://addons.mozilla.org/en-US/firefox/addon/6455
Foxy SEO Tool
Foxy SEO Tool offers tools for search engine optimization (SEO), web traffic and page analysis for webmasters and web professionals.
https://addons.mozilla.org/en-US/firefox/addon/9440