KeyCDN Tools offers a suite of free, one-shot performance diagnostic tools (HTTP/2 test, ping, traceroute, geographic latency). StoreVitals provides automated ongoing ecommerce health monitoring with similar checks plus 30+ more.
KeyCDN's tools are excellent for one-shot diagnostics — when you need to test a single URL right now and don't need history, alerts, or context. StoreVitals overlaps on the most useful diagnostics (HTTP/2, performance, security headers) but adds continuous monitoring, alerting, and the broader ecommerce health audit. Both are free at the entry level. For the recurring 'is my store healthy this week?' question, StoreVitals. For the ad-hoc 'why is this one URL slow?' question, KeyCDN's one-shot tools. They cover different needs in the same general space.