Looks like it's running the same java app that broadbandreports uses for their speed tests.
In fact, if you click on the Graph button, it brings you to BBR.
If you go directly through BBR, on their Tools page, they have 4 servers you can use that use the same applet, and if you have an account there (free, of course), you can choose from hundreds of different servers.
Very helpful, because it allows you to check your speed to different geographic areas, so you can see if you're fast to your neighbor, but slow to the other side of the country. Very useful in diagnosing bandwidth performance problems.