Ahrefs Webmaster Tools - Optimise your website and get more traffic from Google.
Fast.com - Quickly test your internet speed with this fast-loading speed test powered by Netflix.
Dareboost: Website Speed Comparison - Check how fast your website is against your competitors
LibreSpeed - Self-hosted Speedtest for HTML5. Easy setup, examples, configurable, mobile friendly.
Treo Site Speed - Find out how fast your website is for real users
speedtest-cli - Test your download speed using SpeedTest on the command-line