Firefox add-ons for Web-developers!

1.Web developer`s toolbar

Web Developers Learn How to Build Web Sites, Program in HTML, Java and JavaScript.....
https://addons.mozilla.org/en-US/firefox/addon/60

2.Firebug

Edit and monitor CSS, HTML and JavaScript live in any web page.
https://addons.mozilla.org/en-US/firefox/addon/1843

3.ColorZilla

ColorZilla offers You an advanced eyedropper, colorPicker, page Zoomer and other colorful goodies.
https://addons.mozilla.org/en-US/firefox/addon/271/

4.HTML Validator

This plugin displays the number of found errors of the site you are viewing.
https://addons.mozilla.org/en-US/firefox/addon/249

5.YSlow

High performance for web sites.
https://addons.mozilla.org/en-US/firefox/addon/5369

6.FireFTP

FireFTP is simply an FTP client built into the Firefox browser. Important thing it is free and you can flip to it just like any tab in your browser. https://addons.mozilla.org/en-US/firefox/addon/684

7.X-Ray

You can check out all the HTML tags right on the page without using the view page source option.
https://addons.mozilla.org/en-US/firefox/addon/1802

8.Jiffy

Adds a new panel to Firebug for displaying timing measurements for JavaScript applications.
https://addons.mozilla.org/en-US/firefox/addon/7613

9.Pinger

Looks for broken links on page, links that are not working anymore - returning 404 code.
https://addons.mozilla.org/en-US/firefox/addon/10201

10.Speed Dial

With Speed Dial, you can easily access your most used websites.
https://addons.mozilla.org/en-US/firefox/addon/4810

11.The Cooliris 3D Wall

Simply the fastest and most stunning way to browse photos and videos from the Web or your desktop. Effortlessly scroll an infinite '3D Wall' of your content from Facebook, Google Images, YouTube, Flickr, and hundreds more.
https://addons.mozilla.org/en-US/firefox/addon/5579

12.Video DownloadHelper 4.6.4

The easy way to download and convert Web videos from hundreds of YouTube-like sites. This works also for audio and picture galleries. https://addons.mozilla.org/en-US/firefox/addon/3006

13.SenSEO 1.1.0

SenSEO is an extension checking the most important on-page-SEO-criteria and calculating a grade of how good your site fulfills these criteria.https://addons.mozilla.org/en-US/firefox/addon/9403

14.Page Speed

Page Speed is an open-source Firefox/Firebug Add-on. Webmasters and web developers can use Page Speed to evaluate the performance of their web pages and to get suggestions on how to improve them.
https://dl-ssl.google.com/page-speed/current/page-speed.xpi

15.NoDoFollow

Just a simple extension to highlight links in a page according to nofollow / dofollow status.
https://addons.mozilla.org/en-US/firefox/addon/5687