SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
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.
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!
SEOmator - SEO website analysis & audit tool
Majestic - Majestic - Link intelligence tools for SEO and Internet PR and Marketing. Site Explorer shows inbound link and site summary data.