SEO Tools & Software
This collection of tools and software can help make the search engine optimization more efficient and effective. It is worth repeating (this has been mentioned many times elsewhere on this site) that no SEO tool is a magic solution to better rankings--gaining improvements in search engines takes consistent and high quality SEO activities either in form of SEO services, or personal effort.
https://www.google.com/webmasters/
For many people the name of the game is 'How to Beat Google', but Google is not the enemy, and provides many resources for webmasters. Even if you disagree with Google's recommendations, their tools provide a wealth of knowledge about how Google sees your website. The most important tool which Google provides is the Google Search Console, with the Mobile-Friendly Test at a close second.
Price: Free
http://www.screamingfrog.co.uk/seo-spider/
Screaming Frog is a desktop software which crawls website links and compiles a list of SEO-related data and statistics which can be used by an search engine optimizer to troubleshoot basic SEO issues.
Price: Free - $99/year
http://www.raventools.com
Raven Tools is an online marketing platform which assists marketers by providing tools which allows marketing activities including to generating reports, researching links, doing SEO audits, and managing social media campaigns.
Price: $99/mo-$249/mo
http://www.moz.com/
Moz (formerly SEO Moz) is a search engine optimization platform which offers tools to help SEOs recognize website issues, address problems, research links, and find keywords.
Price: $99-$599/mo
http://www.majesticseo.com/
Majestic SEO is a link intelligence tool which allows search engine optimizers and link developers to research and discover link building opportunities.
Price: Free-$1,599/mo
http://www.semrush.com/
SEM Rush is a marketing platform which offers tools and data to help with competitive intelligence research for search engine marketers and marketing professionals.
Price:$69-$149/mo
http://www.authoritylabs.com/
Authority Labs is a ranking report platform which offers webmasters and marketers the ability to track their SERPs results on a daily basis.
Price: $9-$450/mo
http://www.advancedwebranking.com/
Advanced Web Ranking offers web-based ranking reports as well as other tools to facilitate search engine and social media marketing. AWR offers both a desktop software as well as a cloud-based service.
Price (cloud): $49-$499/moPrice (software): $199-$2,999 lifetime license
http://www.wordtracker.com/
Wordtracker is one of the oldest keyword research tools which allows search engine marketers to develop a targeted keyword list.
Price: $27-$99/mo
http://www.keywordspy.com/
Keyword Spy is a competitive intelligence tool which allows search engine marketers to discover competitors? campaign keywords, ad copies, and other information.
Price: $89-$139/mo (also offers enterprise option)