Majestic - Majestic - Link intelligence tools for SEO and Internet PR and Marketing. Site Explorer shows inbound link and site summary data.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
Ahrefs - Ahrefs is a toolset for SEO and marketing. We have tools for backlink research, organic traffic research, keyword research, content marketing & more. Give Ahrefs a try!
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.
SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
SpyFu - SpyFu helps companies determine where the company needs to go and how to get there. Improve experience with clients by watching trends and planning new strategies.