Siteimprove - Consider the Siteimprove Intelligence Platform the newest member of your team.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
Koalati - Automated website testing and quality control tools for developers and agencies.
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!
RankScience - Advanced Content Optimization Software for SEO
UpSeo - UpSeo is a best-in-class website traffic generator, allowing you to get more potential visitors to your website and enhance conversions.