Fast.com - Quickly test your internet speed with this fast-loading speed test powered by Netflix.
Check a Site - Scan websites for over 700 quality problems
LibreSpeed - Self-hosted Speedtest for HTML5. Easy setup, examples, configurable, mobile friendly.
Beta Family - 50,000 testers to test your app
speedtest-cli - Test your download speed using SpeedTest on the command-line
BrokenLinkCheck - Free Broken Link Checker / Online Dead Link Checking Tool - find bad hyperlinks