Serpstat - Search analytics, Rank tracking, Backlink analysis and Site Audit tool.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
SE Ranking - All-in-One cloud-based SEO software for agencies, marketing teams and webmasters
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!
Advanced Web Ranking - Advanced Web Ranking (AWR) is a robust rank tracker, specially designed for large amounts of keywords, which makes it the ideal solution for agencies and medium-to-large in-house teams.
SEO Tools Centre - SEO Tools Centre provides SEO checker services for websites.