I’m always asked which are some of the best SEO tools and honestly there are so many other there that it’s hard to decide which ones are great, which ones are good and which ones are useless.  There are many out there that are useless or only slightly beneficial.  I’ll write about the major tools that I use and let you decide for yourself if you use them.  I’ll categorize these seo tools in a few sections.

Page Information - Want to know a bit more about the page?
SEO Plugin for Firefox - With this tool you can check out the page rank, anchorlinks and other important information?  This is a very important tool and it doesn’t require you to visit a bunch of websites for the information.
Website Grader Tool - This tool is great to see the basics of a certain website and critizes it based on basic SEO information. A good tool for beginners.
Duplicate Content Checker - Duplicate Content can be a serious problem for SEO. Search Engines know when content is not original and they lower a ranking for that particular page.
Alexa Rank Comparison - Alexa, owned by Amazon, is a popular traffic estimator. This tool is useful to see traffic estimates between two websites.
Code-to-Text Ratio Tool - The more text on a website the more likely you’ll have targeted content. Google and other search engines rank pages on relevancy.

Keyword Tools - What to know more about specific keywords?
Google Keyword Tool - The most basic tool for Keyword research, Google’s tool is simple yet resourceful.
SEOBook’s Keyword Tool - Similar to Google’s but provides more information. Very useful.
SEMRush Keyword Tool - Best Keyword tool out there. Gives you a bunch of useful information including websites that appear on organic and paid listings.

Link Tools - Tools that give you information about Linking.
Link Popularity Tool - Easy to use tool to determine how popular a specific link is.
Site Linking Analyzer - Another great tool that checks the anchor text and information about links on a website.
Link Popularity Checker - Another link popularity checker.

Other Tools - Other useful tools that will help.
Search Engine Saturation Tool - See how many pages a search engine has indexed for your website.
Google Webmaster Tools - Great tool to update sitemaps for Google and to see search queries for your website.
Google Analytics - Best and Easiest to use Analytical software out there. It’s also free.

There are a lot of tools out there.  I use a bunch of other tools as well but these tools are the some of the first I go for where I try to get information when starting an SEO campaign.  If you have any other tools that you use, feel free to share them in the comments.