Sitebeam - Spelling mistakes, SEO, load speed, social media, code, W3C, accessibility & more in one tool.
Ryte - Ryte is a web-based software invented for technical optimization for search engines and improvement of websites.
Website Grader - Grade your website's strengths and weaknesses in seconds.
RankScience - Advanced Content Optimization Software for SEO
Siteimprove - Consider the Siteimprove Intelligence Platform the newest member of your team.
SISTRIX - SISTRIX toolbox is an SEO tool for professionals helping reputable companies to constantly improve their websites.