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 49–64 of 64 documents

Document	Version
426 Upgrade Required HTTP 426 Upgrade Required is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
428 Precondition Required HTTP 428 Precondition Required is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
429 Too Many Requests HTTP 429 Too Many Requests is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
431 Request Header Fields Too Large HTTP 431 Request Header Fields Too Large is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
451 Unavailable For Legal Reasons HTTP 451 Unavailable For Legal Reasons is a 4xx client error status code in the IANA HTTP Status Code Registry.	v1
500 Internal Server Error HTTP 500 Internal Server Error is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
501 Not Implemented HTTP 501 Not Implemented is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
502 Bad Gateway HTTP 502 Bad Gateway is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
503 Service Unavailable HTTP 503 Service Unavailable is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
504 Gateway Timeout HTTP 504 Gateway Timeout is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
505 HTTP Version Not Supported HTTP 505 HTTP Version Not Supported is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
506 Variant Also Negotiates HTTP 506 Variant Also Negotiates is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
507 Insufficient Storage HTTP 507 Insufficient Storage is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
508 Loop Detected HTTP 508 Loop Detected is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
510 Not Extended HTTP 510 Not Extended is a 5xx server error status code in the IANA HTTP Status Code Registry.	v1
511 Network Authentication Required HTTP 511 Network Authentication Required is a 5xx server 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