Operations whose document establishes no authentication requirement and whose endpoint refuses an anonymous request anyway, observed on 2026-09-10. A server that answers 401 is alive - this is not a list of broken things, it is a list of things an agent cannot plan around from the document alone.
441 records across 32 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.