One of the reasons why Firefox is such a popular web browser, with tens of millions of users around the world, is its extensive support for addons. There are several great addons for Firefox that can help web developers work more effectively. Here are nine of the best.

• Firebug

One of the most popular Firefox addons of all time, Firebug makes web designing a lot easier, by providing tools that let you determine the color, height, and width of HTML elements, inspect the structure of the web page, discover what CSS styles are used for what elements, and many other features. Firebug is extremely powerful, but to use it effectively you will have to read the documentation offered by its developers.

• Web Developer

A complete set of web design tools that a web developer needs daily, this addon includes useful features like ability to view the CSS of a web page, measure design elements, or see image alt attributes. Once you add it to Firefox, a toolbar with menus will appear in Firefox, through which you can perform the functions noted above, and many more besides.

• TableTools2

A popular web development addon, TableTools2 lets you copy, sort, search, chart, filter, and rearrange HTML tables. Notable features include auto-detection of multiple data types like date & time and currency, support for multiple-column sort, and drop-down list filtering. TableTools2 is feature-packed, coming with many, many useful tools that make the handling of HTML tables a lot easier. Definitely a must-have addon for any website designer.

• Form History Control

Lets you manage form history entries, including search, edit, import and export, and cleanup. Comes with a useful auto-save feature for text entered in all forms, which prevents misfortunes. Useful because it lets you store form history data selectively, on only certain web pages.

• HTML Validator

Much like a spellchecker in a word processing software helps you prevent typos and common grammar errors, so does HTML Validator helps your write good HTML for webpages. It points out the bits of code that do not comply with the HTML standards, and tells you why.

• ColorZilla

This addon comes with an eye-dropper and a color picker, making it easy for you to identify exactly what colors are used on web pages. ColorZilla is simple and convenient, which is why it is so popular.

• QuickJava

With QuickJava you can turn off Java and Javascript, as well as Flash, Images, Cookies, Images, and others quickly, directly from the Toolbar, or the Statusbar. To use it, click the corresponding icon to disable an option – the icon will change color. If you want to turn all options on with a click, middle click an icon. QuickJava is a light and convenient addon that doesn’t take too long to learn.

• SEO Doctor

With SEO Doctor it’s easy to assess whether a web page is SEO friendly. This addon analyzes a web page and gives it a SEO score, highlighting the areas where improvements can be made. SEO Doctor shows link structure, helps track page rank flow, detects non-indexable web pages, and can export data into spreadsheets, allowing you to easily analyze it. All in all, this is one of the best SEO diagnosis tools you can get.

• Page Speed

Analyzing web page speed and offering advice on how to improve it, Page Speed is an invaluable addon for web designers. It is a well-known fact of web design that if a website does not load in a few seconds, the visitor will likely leave it.

The addons listed here are among the best rated, most popular, and most frequently updated. But there are several other interesting Firefox addons for web developers in the Firefox Extension Directory, so do check them.

Aishwarya Vohra writes on different topics relating to the tech world. She is a writer and a designer who loves all things creative. You can visit her sites for great web design tutorials and web design templates.