HTTP status reference
Instant search. Filter by code or keyword. RFC 9110 + de-facto extensions (418, 451, 419…).
Initial part of a request received, continue with the body.
Server switching protocols, e.g. HTTP/1.1 → HTTP/2 or to WebSocket.
WebDAV — processing, no final response yet (deprecated).
Preload hints before the final response.
Standard successful response.
Resource created. Include Location header.
Request accepted, processing not finished.
Response modified by a transforming proxy.
Success, no body. Typical for DELETE / PUT idempotent.
Tell the client to reset the form.
Range request fulfilled.
WebDAV — multiple status codes inside body.
WebDAV — DAV binding already enumerated.
Delta encoding result.
Multiple representations available.
Resource permanently moved. Use Location.
Temporary redirect. POSTs may switch to GET.
POST redirects to GET at Location.
Conditional GET hit cache.
Like 302 but preserves method.
Like 301 but preserves method.
Malformed request, client should not retry.
Authentication required or failed.
Reserved. Some APIs use for quota.
Authenticated but not authorized.
No resource at this URI.
Method known but disallowed.
Content negotiation failed.
Proxy auth needed.
Client too slow.
Resource state conflict — typical for ETag mismatch.
Permanently removed, do not retry.
Content-Length header missing.
If-Match / If-Unmodified-Since failed.
Body exceeds server limit (was 413 Payload Too Large).
URI longer than server can process.
Content-Type not accepted.
Invalid Range header.
Expect header expectation not met.
RFC 2324 April Fools. Some CDNs use to drop traffic.
Server cannot produce a response for this combination.
Validation error — well-formed but semantically wrong.
WebDAV resource locked.
Previous request failed.
Replay risk (0-RTT TLS).
Client must upgrade protocol.
Conditional request mandatory.
Rate-limited. Include Retry-After.
Headers exceed limit.
Censored by court / law.
Generic server failure. Fix and log.
Feature not supported.
Upstream gave invalid response.
Overloaded or maintenance. Use Retry-After.
Upstream took too long.
Protocol version refused.
Content negotiation loop.
WebDAV — no space.
WebDAV — infinite loop.
Further extensions required.
Captive portal in front.