Majestic - Majestic - Link intelligence tools for SEO and Internet PR and Marketing. Site Explorer shows inbound link and site summary data.
Screaming Frog - Screaming Frog is search engine marketing agency offering search engine optimisation and pay-per-click advertising services.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Brightedge - BrightEdge is the leading content performance marketing platform, helping more than 1,200 customers generate more organic traffic. BrightEdge is based in San Mateo, CA with offices in New York, Seattle, Chicago, Tokyo, Sydney, and London.
SEOmator - SEO website analysis & audit tool