SEMRush - All-in-one Marketing Toolkit for digital marketing professionals.
Really Good UX - A library of screenshots for UX inspiration
SEO Site Checkup - Find comprehensive search engine optimization (SEO) tools for your site.
Usability.gov - Resource for user experience (UX) best practices & guides
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.
UX Check - Easy heuristic evaluations on your website (chrome ext.)