What is an HTTP Status Code Lookup?
Status codes carry precise meaning: 301 vs 302 changes your SEO, 401 vs 403 changes your auth flow, 502 vs 504 points at different broken layers.
This reference covers the codes you will actually meet, each with a practical one-line explanation, filterable by number or keyword.
Frequently asked questions
401 or 403?
401: not authenticated: log in. 403: authenticated but not allowed, logging in again won’t help.
301 or 302 for a moved page?
301 (or 308) for permanent moves: search engines transfer ranking. 302/307 only for genuinely temporary detours.
502 vs 504?
Both blame the upstream: 502 = it answered garbage, 504 = it never answered in time.
Is 418 real?
Yes: an April Fools RFC from 1998. Some real servers return it for blocked requests as an easter egg.