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.
Lumar - (Previously DeepCrawl) Hosted SEO spider to analyze and find problems with websites.
Moz - Backed by industry-leading data and the largest community of SEOs on the planet, Moz builds tools that make inbound marketing easy.
Website Checker Tech - WebsiteChecker.Tech is SaaS tool that detects SEO and availability issues of your website, making it easier for you to fix them.
Sitechecker - All-in-one SEO platform including rank tracker, website SEO audit tool and website changes monitoring. Detailed reports by 100+ parameters with how-to-fix guides.