Speedtest.net - Test your Internet connection bandwidth to locations around the world with this interactive broadband speed test from Ookla
Fast.com - Quickly test your internet speed with this fast-loading speed test powered by Netflix.
Testmy.net - Accurately test your Internet connection speed with this powerful broadband speed test. Improve your bandwidth speed with the truth.
LibreSpeed - Self-hosted Speedtest for HTML5. Easy setup, examples, configurable, mobile friendly.
OpenSpeedTest - Broadband Internet Speed Test Unlocked!
speedtest-cli - Test your download speed using SpeedTest on the command-line