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.
Cruip - Landing page templates for startups
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.
Shade - Super easy color contrast insights and recommendations
Smaller - Make your websites load faster
Tilda - Tilda is a platform to produce landing pages, blogs, webpages through its responsive page builder.