SitePerformanceTest.com - Website Performance and Usability Test
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.
GTmetrix - GTmetrix is a free tool that analyzes your page's speed performance. Using PageSpeed and YSlow, GTmetrix generates scores for your pages and offers actionable recommendations on how to fix them.
Smaller - Make your websites load faster
CheckPageSpeed.com - Website Speed and Performance Analyzer
Pageradar.io - Pageradar is a solution designed to help you improve your web performance and monitor it daily, for better SEO.