In this article by Kristi Hines, you can find six indispensable free and freemium SEO tools for keyword research, on-site optimization, link building, suggestions, and monitoring keyword rankings.
Here in summary the tools presented and a brief description about them.
1. AdWords Keyword Tool for Keyword Research:
All SEO campaigns should begin with keyword research. Google AdWords Keyword Tool is your best bet for a free keyword research tool.
2. SEO Book for a Keyword Research & On-Site Analysis:
With a free account, you have access to the tools as a keyword density analyzer, a page comparison tool to find keywords, an ad group generator for AdWords, and others.
3. SEO Site Tools for On-Site Analysis & Suggestions:
If you are using Google Chrome, then the SEO Site Tools is a must have extension for your browser. You can see the PageRank of any page you are browsing immediately in your extensions’ toolbar and you can get the rest of the information by clicking on the magnifying glass.
4. Open Site Explorer for Competitor Backlink Research:
A great way to find link opportunities for your website’s link building campaign is to research the backlinks of competitor websites. SEOmoz’s Open Site Explorer allows you to enter a domain and view that domain’s backlinks.
5. SEMrush for Paid Search & Keyword Ranking Analysis:
If you are working on paid search, then you might be curious about keywords competitors are ranking for organically and the CPC for those keywords. SEMRush will answer those questions.
6. Authority Labs for Monitoring SEO Campaign Results:
What is the point of a good SEO campaign if you are not monitoring the results? Authority Labs is a great tool for keeping tabs on your keyword rankings by simply entering your domain and the keywords you want to track.
Get in depth info for each one and how to best leverage its capabilities by reading the
full article here: http://j.mp/Ax1Pv2
Via Giuseppe Mauriello, Robin Good