A 5xx is the one observation here that can be weather. Most of these are held at `needs_second_observation` rather than confirmed for exactly that reason, and the nightly re-check either confirms them or drops them. 13 have already been repaired since we started watching.
779 records across 591 subjects, observed 2026-09-10. Every one carries a check you can run in a single request.
All subjects · the whole registry, machine-readable
Asking about something not listed here, before you use it — one request, no key: GET https://apidefects.com/check?tool=<identity>. never_examined is an answer too, and it is not a clean bill of health.
This is not a list of good APIs or bad ones. It is a list of observations, each dated and each disprovable in one request. Absence from it means an operation was not examined, not that it is fine.