Website Speed Test and Performance Tools
https://gtmetrix.com/ (Unfortunately this is no longer free for basic reports)
https://www.dareboost.com/en/analysis
https://www.site24x7.com/web-page-analyzer.html
https://www.dotcom-tools.com/website-speed-test.aspx
https://www.uptrends.com/tools/website-speed-test
https://tools.keycdn.com/speed (speed, performance, header checker, etc)
Additional Tools
https://webspeedtest.cloudinary.com/ (Image analysis tool)
https://seositecheckup.com/ (SEO checker)