Mozilla Firefox Add-ONS has become an extremely powerful and useful tool for web developers. Using the right add-ons, it will be developers best dream. And with the release of Firefox 30, it got even easier.

This article features 30 essential Firefox 7 add-ons for web developers. Please note that few of the extensions below are still marked as ‘experimental’, but have been tested and do work perfectly well with Firefox 30. This article is continuously updated as we discover new tools. If you have suggestions, please let us know in the comments.

SEO Site Tools, Site Analysis 

Shows Google PageRank of the current page. More features including IP Geolocation, Domain Whois, SEO Stats, Pages Indexed, Backlinks, Alexa Rank, Social Analysis and many other SEO Tools.

YSlow 

YSlow analyzes web pages and suggests ways to improve their performance based on a set of rules for high performance web pages.

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.

Page Speed Monitor

Get the page load times of any web page! app.telemetry Page Speed Monitor shows offset and duration of each step during the page load based on W3C navigation timing.

FireRainbow | Firefox Add-ONS

This is a nifty add-on that adds JavaScript highlighting to the Firebug script browser.

Greasemonkey 

Customize the way a web page displays or behaves, by using small bits of JavaScript.

Link Checker 

CSSsir 

This CSS3 generator will be useful not only for web-masters and designers but also for common users.

Fireshot

Empty Cache Button

NoDoFollow

Just a simple extension to highlight links in a page according to nofollow / dofollow status.

Adblock Plus

Primary goal of Adblock Plus is blocking advertisements while browsing. This add-on thus allows you to regain control of the Internet and view the web the way you want to. For removing advertisements, it will block all requests made for ads. Since it blocks from the root we can save bandwidth. Firefox Add-ONS

Awesome Screenshot

Are you an active blogger? Then I think Awesome Screenshot ‘ll be really awesome for you!!!. Awesome Screenshot is a screen capture add-on that captures the entire page or crop any portion, annotate it with rectangles, circles, arrows, lines and text,erase sensitive information, save to Local or upload to awesomescreenshot.com and get a shareable link.

BetterPrivacy

Ever wondered why you are still tracked though you tried everything to prevent it?
BetterPrivacy is a safeguard which protects from usually not deletable LSO’s on Google, YouTube, Ebay…

CodeBurner for Firebug

CodeBurner integrates with Firebug to extend it with reference material for HTML and CSS. CodeBurner’s core functionality is centered around a new Reference panel, which contains a search tool for looking up HTML elements, attributes, and CSS properties. It also hooks into context-menus in the HTML and CSS panels, the DOM crumb trail, and the Inspector, adding options to look up a selected item (ie. search for it in the Reference panel) or to view a code example.

Color Zilla

If there’s a color on a Web page that you like, ColorZilla will find the precise code for it and allow you to paste it into your coding program. You can also create custom colors with its built-in palette browser. It saves the most-used colors for easy access later on. It’s powerful, it’s simple, it’s a must-have.

Console2

Console² replaces the JavaScript Console with what could be the next generation Error Console. Console² let’s you display errors filtered by type (Errors, Warnings, Messages), language (JavaScript, CSS, XML) and context (Chrome, Content). Furthermore it provides a simple search box (as seen in the History and Bookmarks sidebars), hiding of duplicates, sidebar optimizations, a customizable toolbar and some more accessibility improvements. From v0.5 includes the Console Filter extension previously available separately from the Console² website.

DownloadHelper

DownloadHelper allows you to download and convert web videos directly from your browser with minimum effort. While surfing the Web , when DownloadHelper detects, the icon gets animated and a menu allows you to download files by simply clicking an item. You can download anything from YouTube, MySpace, Google videos, DailyMotion, Porkolt, iFilm, DreamHost and others.

DownthemAll

DownThemAll is a Mozilla Firefox extension that adds new advanced download capabilities to your browser. dTa is easy-to-use,powerful,fast and reliable. By using DownThemAll you can download all the links or images contained in a webpage and refine your downloads to get only what you really want. DownThemAll features an advanced accelerator that increases speed up to 4x and number of parallel connections at any time. You can pause and resume downloads at any time. Once of the best feature is the ability to add meta links or mirrors manually to download a file from different servers at the same time. DownThemAll is open-source and freeware.

EditCSS

EditCSS is a stylesheet modifier in the Sidebar.

FastestFox – Browse Faster

Save time by speeding up repetitive tasks. Get faster, parallelized downloads, see definitions, auto-load the next page, improve searching, and more. FastestFox will dramatically enhance your productivity!

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.

Firefox UI Fixer

Change location of Status Bar Icons, Firefox Menu Button and Menu Bar and more.

FireFTP

FireFTP is a free, secure, cross-platform FTP/SFTP client for Mozilla Firefox which provides easy and intuitive access to FTP/SFTP servers. Along with transferring your files quickly and efficiently, FireFTP also includes more advanced features such as: directory comparison, syncing directories while navigating, SFTP, SSL encryption, search/filtering, integrity checks, remote editing, drag & drop, file hashing, and more.

Firepicker

Firepicker integrates with Firebug and adds a small color picker dialog when editing a CSS rule in Firebug. Firepicker scans for values that can be parsed as CSS colors (#abc, rgb(1,2,3), blue, red etc.) and displays them in a drop-down list right below the firebug’s CSS editor box. Clicking on the color value in the drop-down brings up a color picker dialog.

FireShot – Webpage Screenshots

FireShot creates screenshots of web pages entirely.

FoxTab

3D in your browser! FoxTab brings innovative 3D functionality to your Firefox.

FoxyProxy

FoxyProxy is an advanced proxy management tool that completely replaces Firefox’s limited proxying capabilities. It offers more features than SwitchProxy, ProxyButton, QuickProxy, xyzproxy, ProxyTex, TorButton, etc. It automatically switches an internet connection across one or more proxy servers based on URL patterns. Basically, FoxyProxy automates the manual process of editing Firefox’s Connection Settings dialog. Proxy server switching occurs based on the loading URL and the switching rules you define.

GReader Panel

It can display mobile Google Reader in a panel.

HTML5 Validator

HTML5 Validator adds a ‘HTML 5 Validator’ context menu item to a page’s context menu.

HTML5toggle

HTML5toggle provides a button which makes it easy to turn on or off the HTML5 support in Firefox 4. Given that HTML5 support is still evolving, some websites do not work as expected when HTML5 support in Firefox 4 is enabled.

IE Viewer

This add-on lets you preview websites in IE. It helps when checking for cross browser compatibility. You can also set some websites to always open in IE viewer if there are some compatibility issues.

Image Zoom

Adds zoom and rotation functionality for images…

NoScript

The best security you can get in a web browser!
Allow active content to run only from sites you trust, and protect yourself against XSS and Clickjacking attacks.

Personal Menu (Personal Firefox Button)

Users will be able to edit the Firefox Menu by using this addon. Moreover, they can put several items into Firefox Menu which are Bookmark Items, History Items, Configuration(about:config), Restart.

Rainbow Color Tools

Color picker and eyedropper + saving colors and trying out colors with drag and drop.

Scriptish

A User Script Extension Manager for Firefox (fork of Greasemonkey).

SeoQuake

Seoquake is a Firefox SEO extension aimed primarily at helping web masters who deal with search engine optimization (SEO), social media optimization (SMO) and internet promotion. Seoquake allows to investigate many important SEO parameters.

Super Start

Just another visual bookmarks (like speed dial or fast dial) and a simple todo-list in your homepage. Go to add-ons manager or right click for options.

View Source Chart

View Source Chart lets you inspect the DOM—and learn HTML—at lightning speed. Eyesight is the most efficient way for the human brain to process information. By placing visual boundaries where they already exist invisibly, View Source Chart enables you to take in DOM structure and hierarchy as fast as your brain possibly can.

Web Developer’s Toolbar

Web Developer`s tool bar probably will become one of the best plugins You`ve ever seen. It comes with his own tool bar that gives many useful tools for analyzing, validating and optimizing web-pages. The great thing about this plugin is that it’s on a few different browsers, so if you switch between them you will be able to use the same plugin on all.

what are your favorite Firefox 7 addons for web developers? Feel free to share your useful additions in the comments section below.