Fast.com - Quickly test your internet speed with this fast-loading speed test powered by Netflix.
Website Speed Ranker - Compare how fast your website loads vs your competitors
LibreSpeed - Self-hosted Speedtest for HTML5. Easy setup, examples, configurable, mobile friendly.
Textalyzer - Analyze text readability and SEO parameters
speedtest-cli - Test your download speed using SpeedTest on the command-line
SanityCheck - Get the exact data you need from Google Search Console.