Slowy app - Simulate custom Internet connection speeds for testing
speedtest-cli - Test your download speed using SpeedTest on the command-line
Speedtest by Ookla - Measure your ISP's performance in a click
Global Website Speed Test - Test website load speed from 18 cities, including 3 in China
Meteor - Meteor is a set of new technologies for building top-quality web apps in a fraction of the time.
Sentry.io - From error tracking to performance monitoring, developers can see what actually matters, solve quicker, and learn continuously about their applications - from the frontend to the backend.