HTTP Status Codes Reference & Search (IANA Registry)
Search HTTP status codes by number or keyword and see the official IANA name, the defining RFC and a plain-language explanation. Unassigned codes are shown as unassigned, never guessed.
- Runs in your browser with cited reference data
Search by a three-digit code (e.g. 404), its first digits (e.g. 41), a class (e.g. 5xx) or keywords (e.g. redirect, timeout).
Result
- 404Not Found
The server did not find a current representation of the resource, or does not want to reveal that one exists. It does not say whether this is temporary or permanent.
RFC 9110 defines this code as heuristically cacheable: caches may reuse it even without explicit freshness information.
How to use
- Type a code (e.g. 404), its first digits (e.g. 41), a class (e.g. 5xx) or keywords.
- The official name, an explanation and links to the defining RFC appear. Use “Show all” for the full list by class.
FAQ
What does a code that is not listed (such as 499) mean?
Codes left unassigned in the IANA registry have no official meaning. Under RFC 9110, a client treats an unrecognized code like x00 of its class (400 for 499).
Can I use 418?
418 is reserved because the joke RFC 2324 used it, so it cannot currently be assigned to anything else. It has no official status code meaning.
How current is the data?
It is the IANA registry (last updated 2025-09-15), checked on 2026-11-06. Entries that may change later, such as temporary registrations, are marked.
Notes & limitations
- What you enter is processed only on this page and is not sent to YUCTS servers.
- Only codes registered with IANA are covered. Meanings used by specific products such as nginx or CDNs are not shown.
- The explanations are this site’s short summaries of the definitions. Follow the “Defined in” links for the exact specification text.
- The registry can change (for example, 104 is a temporary registration until 2026-11-13). Check the IANA website for the current state.
Data sources
- IANA — Hypertext Transfer Protocol (HTTP) Status Code Registry(opens in a new tab) (last updated 2025-09-15) — Checked on: 2026-11-06
- RFC 9110: HTTP Semantics — Section 15 Status Codes(opens in a new tab) (June 2022) — Checked on: 2026-11-06
- RFC 4918: HTTP Extensions for WebDAV (removal of 102)(opens in a new tab) — Checked on: 2026-11-06
- RFC 6585: Additional HTTP Status Codes(opens in a new tab) — Checked on: 2026-11-06
- IETF — Status change of HTTP experiments to Historic (RFC 2774)(opens in a new tab) — Checked on: 2026-11-06
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