Crazyegg

Crazy Egg allows website owners to create tests to figure out what users are doing on their site. CrazyEgg claims their mouse tracking solution collects "more than 88% of the data you would collect using classic eye tracking tools". This is clearly bullshit.

Spyfu

Spyfu is the all-in-one one-stop Internet Marketing platform allowing you to easily analyze your competitors. SpyFu helps you spy on your competitors use their search marketing secret formula to improve your own business. Deep research or quick glimpses at their ad habits show you what works and what to avoid when you're connecting with your target audience.

Majestic

Majestic SEO is a software package focused on providing information for link building, reputation management, competitive link analysis and website traffic analysis. Overall, Majestic SEO is easy to use and effective for seeing what kinds of backlinks your site has developed over time.

Moz

Moz is a top SEO tool provider that uses both basic and advanced research tools to help you in your search engine optimization. Moz offers keyword research tools and a SEO keyword generator; it also offers link analysis that provides detailed information on your inbound links and link quality.

SEMrush

SEMrush is a powerful and versatile competitive intelligence suite for online marketing, from SEO and PPC to social media and video advertising research. You can perform in-depth keyword analysis, dissect paid ad campaigns and content strategies, conduct backlink audits, identify profitable partnerships, track performance in real-time, and gather actionable insights that will strengthen your online marketing efforts.