Guides

Device testing guides

Longer answers to the questions people actually search for — what a good score is, how a test works, and what to do when a result looks wrong. Every guide links straight to the free tool that measures it.

6 guides · 35 free diagnostic tools · Updated November 2026

Looking for a quick answer instead?

The Help Center has short questions and fixes for every tool, and the complete tool index lists all 35 diagnostics in one place.