Speed is not the story.
Every other test hands you a big number and leaves. This one measures what actually decides whether your connection feels good — latency while the line is busy, jitter, the kind of NAT you're stuck behind, which DNS resolvers your network really lets through, and how far you sit from the rest of the world. Then it grades it honestly and tells you the one thing worth fixing.
A line can be fast and still stutter. We watch what happens to your ping while the connection is working hard — the thing that actually ruins calls and games.
A to F, weighted for what you actually do. A weak spot drags the whole grade down, because that is how it feels in real life.
We time a real datacentre on every continent, so you can see whether your provider carries you well beyond its own network.
Your NAT type, whether you are stuck behind carrier-grade NAT, and which DNS servers your own network quietly blocks.