SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
Pro Rank Tracker - Rank tracking & reporting software solution
SEO PowerSuite - Get all SEO tools in one pack - download free edition of SEO PowerSuite and get top 10 rankings for your site on Google and other search engines!
SEOmator - SEO website analysis & audit tool
SEO Tools Centre - SEO Tools Centre provides SEO checker services for websites.