Converter · SOTA RFC 9110 (2022) + http.cat + curl
HTTP Status Code Reference
Search every status code defined by RFC 9110 plus commonly deployed extensions. Compare 401, 403, 404, 409, 422, and 500 meanings, then copy ready-to-run fetch or cURL examples.
Common HTTP Status Codes in RFC 9110
These are the codes people most often compare when debugging APIs. Each definition below follows the current HTTP Semantics specification rather than framework-specific shorthand.
401 Unauthorized
The request lacks valid authentication credentials. The response needs a WWW-Authenticate challenge that tells the client how it can authenticate.
403 Forbidden
The server understood the request but refuses to fulfill it. A 403 can be caused by insufficient credentials or by a policy unrelated to authentication; a server may return 404 instead when it wants to hide that a resource exists.
404 Not Found
The origin server has no current representation for the target resource, or is unwilling to disclose one. The code alone does not say whether the condition is temporary or permanent.
409 Conflict
The request conflicts with the resource's current state. Version-control conflicts and concurrent updates are common examples; the response should give the client enough context to resolve the conflict.
422 Unprocessable Content
The server understands the content type and the request syntax is valid, but it cannot process the contained instructions. Semantically invalid structured data is a typical use case.
500 Internal Server Error
The server encountered an unexpected condition that stopped it from fulfilling the request. It is a general server-side failure, not a signal that the client's request syntax is invalid.
How to Use HTTP Status Code Reference in 3 Steps
- Configure. Search by code (404, 422) or name (Not Found, Unprocessable Content), or filter by category (1xx informational, 2xx success, 3xx redirect, 4xx client error, 5xx server).
- Process. Each code shows: official name, RFC 9110 reference, typical use cases, common headers, and code examples in fetch and cURL.
- Export. Copy a fetch snippet ready for testing, or a cURL command to replay. Toggle http.cat thumbnails for a quick mental association.
Why HTTP Status Code Reference on Pixlane
HTTP status codes signal request outcomes: 200 OK, 404 Not Found, 500 Internal Server Error. But nuances matter: when to use 401 vs 403, 409 vs 422, or the extension code 428 Precondition Required. Pixlane covers every status defined by RFC 9110 and adds widely deployed extension codes with searchable filters, practical use cases, and fetch + cURL snippets.
- RFC 9110 (2022): The current HTTP Semantics standard replaces the semantics from RFCs 7230, 7231, 7232, 7233, and 7235. HTTP caching from RFC 7234 is replaced separately by RFC 9111. The reference uses the current names, including 413 Content Too Large, 418 (Unused), and 422 Unprocessable Content.
- Usage Examples: Beyond definitions: when should you return 409 Conflict vs 422 Unprocessable Content? When is 410 Gone better than 404? Each code includes practical guidance.
- fetch + cURL Snippets: Each entry has a ready fetch(`url`).then(r => r.status === 404) and cURL example with `-w '%{http_code}'`. Paste and test.
- http.cat Integration: Optional fun mode shows an http.cat image beside each supported code, without replacing the standards-based definition.
Frequently Asked Questions
Is 418 I'm a Teapot part of RFC 9110?
No. RFC 9110 lists 418 as '(Unused)' and reserves the number for possible future assignment. The humorous I'm a Teapot behavior comes from RFC 2324 and is still implemented by many frameworks, but it is not the RFC 9110 meaning.
When should I return 401 vs 403?
Use 401 when valid authentication credentials are missing; include a WWW-Authenticate challenge. Use 403 when the server understands the request but refuses it. A 403 does not prove the client is authenticated, because the refusal can be unrelated to credentials.
What's the difference between 409 and 422?
409 Conflict is about a collision with the resource's current state, such as a version mismatch. 422 Unprocessable Content means the content type and syntax are understood, but the contained instructions cannot be processed.
Is this tool free?
Yes. HTTP Status Reference on Pixlane currently requires no signup for core use; tool-specific limits may apply.