The API, this website and the dashboard are checked from outside our own infrastructure, on a schedule, by a service we do not host. That last part is the point: the API runs on a single server, and a monitor living on that server would go down with it and report nothing.
Each check is retried three times, twenty seconds apart, before anything is raised. One failed request is usually a network fault between the checker and us rather than an outage, and treating it as one would make the alerts worth ignoring.
Two limits, so you can judge what this is worth. Checks run every thirty minutes, not every minute, and the schedule is best-effort — it can run late. And they run from one place, so a fault between that place and our region looks the same to it as an outage here.
So this is a floor on how quickly we find out, not a stopwatch. It is why the uptime figure above is still a target rather than a guarantee, and why there is no automatic credit table further down: we would rather owe you a straight answer than compute a percentage from measurements this coarse.
It also means you may still notice an outage before we do. If that happens, tell us — we will treat it as the incident it is, not argue with you about our own graph.