I'm a fan of Firefox mainly for the additional functionality you get from using plugins. In fact, it's always frustrating when I am on someone else's computer, and I don't have access to my own set of "tools" that I use on a daily basis. Simply put, if you aren't using Firefox, you're missing out on a more effective way to work.
Below is a list of some of my favorite SEO plugins. I have also included a short list of web developer plugins that have some crossover into SEO. I know there are other tools out there, so if you have some additional plugins you like to use, please add them in the comments!
Plugins Specifically for SEO
SEO for Firefox
This one is a standard tool for most of the SEOs that I personally know. This plugin gives you a ton of additional information when you do a search on Google. You can see a site's PageRank, age, Yahoo links and other data that can help you when analyzing your competitors.
It also gives you access to a handy little tool called SEO XRay. This sub-tool will show you the meta information, H tag use and internal and external links on a page. There are so many ways to use SEO for Firefox, it's no wonder that it's a standard tool! Aaron Wall (SEOBook) did a great job with this one!
Get it here: SEO for Firefox
This is another great tool from Aaron Wall. If all you want to do is a quick ranking update, Rank Checker is the way to go. This tool is usually quick, and you can export your findings to a CSV document if you want to compare them with previous rankings.
As with any rank checking tool, it is not always 100% accurate. However, it is still a great free way to keep up on all of your keywords.
Get it here: Rank Checker
Do you ever get tired of the Google Toolbar? If you're like me, the only reason you really use the Google Toolbar is to find out the PageRank of the page. Well, with SearchStatus, you can get PageRank, Alexa Rank, Moz Rank and Compete Rank in your status bar. There are many other things that this tool does, but that's what I mainly use it for.
Get it here: SearchStatus
SEO Link Analysis
I consider this plugin to be one of the essentials in my toolbox. This tool works when you go to the Yahoo Site Explorer or into your Google Webmaster account looking for back links. Rather than just seeing what sites are linking back, you can see the anchor text and the PageRank of the page linking back. You can also find out if the link is still there or has a no follow attribute.
This tool is great for spying on your competition. Go to the Yahoo Site Explorer and you will very quickly find out what keywords your competition is targeting. This makes it great for site analysis and competitive analysis.
Get it here: SEO Link Analysis
Helpful Web Development Plugins
If you're going to do SEO, you need to know some of the basics of web development as well. Because of this, I thought it might be helpful to list a few plugins that you can use mainly for web development, but also have a crossover into SEO.
I have loved this plugin ever since I first found it. As an SEO, I find that I am constantly helping to fix web development problems as part of the job. This tool will let you go through a site and find the different elements so you can see where the problems are in the HTML or CSS of the page. You can also make changes to a live site to see what would happen if you tweaked certain things.
Get it here: Firebug
By having your HTML valid, your site is more likely to look the same in the different browsers. This tool will show you where the problems are in your code that could be causing inconsistencies from browser to browser. It also gives you suggestions on how to fix them.
Get it here: HTML Validator
Get it here: Web Developer
Add to the List!
Now it is your turn. Do you have some favorites that I did not include on this list? If so, please add them in the comments below!