Mark Ferree - Open Source Web Development

At one time Firefox was just about the only choice when it came to good web standards support, but luckily times have changed.

There is still one thing about Firefox that makes it the browser of choice for most web developers, a huge library of extensions.

Without further delay, here are my top picks for web development in Firefox.

1. Firebug - It's hard for me to imagine developing sites without Firebug at this point. When it comes to debugging CSS and JavaScript nothing comes close to Firebug. Firebug adds a behind the scenes look at the bottom of your browser window that allows you to view and modify your html, css, and JavaScript.
2. Web Developer - While Firebug is a relative new comer to the Firefox arena, Web Developer has been there as long as I've been using Firefox. Web Developer adds a toolbar to the top of your browser window, giving you t he option to view a whole lot of information about your site. In addition to the huge amount of information, you are able to disable JavaScript and CSS, two very important factors to consider when developing a website.
3. It's All Text! - All though it is not specifically an extension for web development, It's All Text has been extremely useful for me as a web developer. It's All Text puts a tiny edit button in the bottom right corner of any text area, clicking this button will open the contents of that text area in the editor of your choice. Editing html in a textarea can be very difficult, but this is a common task with many of today's content management systems. It's All Text bridges the gap letting you use all the features of your editor, and then save the changes right back to the text area.
4. IE Tab - Have to test your sites in Internet Explorer (who doesn't) and don't want to leave it open? IE Tab lets you open a tab in Firefox that renders the page like the version of IE you have installed on your development machine.
5. HTML Validator - HTML Validator does what it's name says, checks to see if your HTML is valid. Removes the need to check your site in an external validator, and therefore saves time.
6. Dummy Lipsum - A recent find for me, Dummy Lipsum inserts several paragraphs of Lorem Ipsum text into your text area through the contextual menu.
7. Fireform - Fireform allows you to fill out all the forms on a site with your real information, or dummy information that can be randomly created for you. Fireform definitely takes the drudgery out of testing forms, and the multiple profiles are key when testing thing like international shipping.
8. Greasemonkey - Greasemonkey would probably be nearer the top of a hardcore JavaScript geek's list. I use it occasionally to test out a script, or modify the functionality of someone else's application that I don't have access to change.
9. Tails Export - Tail Export tells you if Microformats are available on the page. Microformats allow you to markup information on your page in a standard way that is used throughout the web. Although they have not become very widespread, this extension allows you to make sure your Microformats are working correctly.
10. ColorZilla - ColorZilla gives you a button that when you press it turns on an eye dropper. Useful for quickly finding the hex values of colors on the site you are working on.

Let me know if any of your favorites didn't make it on the list.