HTTP status codes (IANA registry)

Assigned HTTP status codes from the IANA Hypertext Transfer Protocol (HTTP) Status Code Registry, one document per code with its reason phrase, class, and defining reference.

Browse 64 documents Use with your agent

Documents

Showing 25–48 of 64 documents

Document	Version
400 Bad Request HTTP 400 Bad Request is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
401 Unauthorized HTTP 401 Unauthorized is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
402 Payment Required HTTP 402 Payment Required is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
403 Forbidden HTTP 403 Forbidden is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
404 Not Found HTTP 404 Not Found is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
405 Method Not Allowed HTTP 405 Method Not Allowed is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
406 Not Acceptable HTTP 406 Not Acceptable is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
407 Proxy Authentication Required HTTP 407 Proxy Authentication Required is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
408 Request Timeout HTTP 408 Request Timeout is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
409 Conflict HTTP 409 Conflict is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
410 Gone HTTP 410 Gone is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
411 Length Required HTTP 411 Length Required is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
412 Precondition Failed HTTP 412 Precondition Failed is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
413 Content Too Large HTTP 413 Content Too Large is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
414 URI Too Long HTTP 414 URI Too Long is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
415 Unsupported Media Type HTTP 415 Unsupported Media Type is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
416 Range Not Satisfiable HTTP 416 Range Not Satisfiable is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
417 Expectation Failed HTTP 417 Expectation Failed is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
418 (Unused) HTTP status code 418 is listed as (Unused) in the IANA HTTP Status Code Registry.	v1
421 Misdirected Request HTTP 421 Misdirected Request is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
422 Unprocessable Content HTTP 422 Unprocessable Content is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
423 Locked HTTP 423 Locked is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
424 Failed Dependency HTTP 424 Failed Dependency is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
425 Too Early HTTP 425 Too Early is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1

Source, review, and usage

Published on Koskamo by: Koskamo
Version: 65
Documents: 64 documents
Reviewed: 2026-10-04
Last approved change: 2026-10-04
Agent lookups: 19 in the last 90 days
Reuse: IANA HTTP Status Code Registry (iana.org/assignments/http-status-codes); registry data reproduced verbatim with references
Review status: Published by Koskamo; proposed revisions require Koskamo approval

Original sources are linked on each document. Owner approval records a publishing decision; it does not imply independent fact checking.

Use this dataset from an agent

Agents can query it without an account. POST to /api/v1/retrieve, or connect an MCP client and call koskamo_retrieve with dataset: "http-status-codes".

Set up your agent Read documents as JSON

The JSON endpoint returns document text and source links in pages. Use limit and offset to retrieve more records; total gives the dataset size.

retrieve request

curl --fail-with-body 'https://koskamo.com/api/v1/retrieve' -H 'Content-Type: application/json' --data-raw '{"query":"429 Too Many Requests","dataset":"http-status-codes","top_k":3}'

Change history

Every change that reached this dataset. Proposals from contributors land only after Koskamo approves them.

Published by Koskamo2026-10-04
511 Network Authentication Required · v1
Published by Koskamo2026-10-04
510 Not Extended · v1
Published by Koskamo2026-10-04
508 Loop Detected · v1
Published by Koskamo2026-10-04
507 Insufficient Storage · v1
Published by Koskamo2026-10-04
506 Variant Also Negotiates · v1
Published by Koskamo2026-10-04
505 HTTP Version Not Supported · v1
Published by Koskamo2026-10-04
504 Gateway Timeout · v1
Published by Koskamo2026-10-04
503 Service Unavailable · v1
Published by Koskamo2026-10-04
502 Bad Gateway · v1
Published by Koskamo2026-10-04
501 Not Implemented · v1