Smaller - Make your websites load faster
Textalyzer - Analyze text readability and SEO parameters
Website Grader - Grade your website's strengths and weaknesses in seconds.
SEO Analyzer By Neil Patel - A free SEO analyzer for your site
Website Speed Ranker - Compare how fast your website loads vs your competitors
Checkbot - Checkbot will boost the SEO, speed and security of your site by checking you're following 50+ web best practices. Browser extension with free and paid plans.