One Page Papers

Reference sheets · 2022

HTTP Status Codes

Roy T. Fielding, Mark Nottingham, Julian Reschke, IANA

Reference sheet · RFC 9110, Section 15 · IANA registry of 15 September 2025

R. Fielding, M. Nottingham, J. Reschke, Editors · and the IANA Hypertext Transfer Protocol (HTTP) Status Code Registry

The poster PDF, wallpaper

Retrieved
27 September 2026
License
MIT (compilation); data: RFC 9110 (IETF Trust), IANA registry (CC0 1.0)
Rights holder
one-page-papers (compilation); IETF Trust and the authors of RFC 9110 (quoted text)
Language
English

Registry: “both IANA and IETF affirm that any applicable rights that they may have in the Protocol Registries are subject to the Creative Commons CC0 1.0 dedication”. RFC 9110, IETF Trust Legal Provisions 5.0, Section 3.c.iii: a license “to copy, publish, display and distribute unmodified portions of IETF Contributions and IETF Documents and translations thereof, provided that: (x) each such portion is clearly attributed to IETF and identifies the RFC or other IETF Document or IETF Contribution from which it is taken”.

  • Codes and reason phrases: IANA HTTP Status Code Registry, updated 2025-09-15, CC0 1.0. Definitions: first sentences quoted unmodified from RFC 9110, Section 15, by the IETF; section numbers refer to RFC 9110. Copyright (c) 2022 IETF Trust and the persons identified as the document authors. Compilation: MIT.
  • Codes without a definition are registered by the document named after their reason phrase.
  • rfc-editor.org/rfc/rfc9110 · iana.org/assignments/http-status-codes
About this edition and its rights

Edition

Two sources, both retrieved on 27 September 2026. (1) The IANA Hypertext Transfer Protocol (HTTP) Status Code Registry, https://www.iana.org/assignments/http-status-codes/http-status-codes-1.csv, last updated 2025-09-15: all 75 rows are set in order, 64 assigned codes and 11 unassigned values or ranges, with the value, the description (the reason phrase) and the reference as the registry gives them; a parenthesis that closes a description (“TEMPORARY - registered 2024-11-13, extension registered 2025-09-15, expires 2026-11-13” for 104, “OBSOLETED” for 510) is set on its own line under the phrase, the brackets around references are dropped, “RFC9110” style references are set “RFC 9110”, two references of one code are parted by a middle dot, and for codes defined by RFC 9110 the reference is shortened to its section number. (2) RFC 9110, HTTP Semantics (STD 97, June 2022), the RFC Editor plain-text edition, which is not paginated: from Section 15 the first paragraph, the second with its list of the five classes, the third (extensibility) and the first paragraph of Section 15.1; for each class the title of its section (15.2 to 15.6) and the first sentence of its first paragraph; for each of the 46 codes that RFC 9110 defines, the first sentence of the first paragraph of its section, unmodified (internal references such as “(Section 7.7)” are kept). Line breaks of the plain text are reflowed. Nothing else is taken from RFC 9110. The header and the footer are written for the poster.

Rights

License notice: “Registry: “both IANA and IETF affirm that any applicable rights that they may have in the Protocol Registries are subject to the Creative Commons CC0 1.0 dedication”. RFC 9110, IETF Trust Legal Provisions 5.0, Section 3.c.iii: a license “to copy, publish, display and distribute unmodified portions of IETF Contributions and IETF Documents and translations thereof, provided that: (x) each such portion is clearly attributed to IETF and identifies the RFC or other IETF Document or IETF Contribution from which it is taken”.”

The layout and the selection are an original compilation under the MIT license of this repository. Data: IANA Hypertext Transfer Protocol (HTTP) Status Code Registry, https://www.iana.org/assignments/http-status-codes/, under the Joint Statement of IANA and IETF Concerning Copyright Rights in the Protocol Registries of 10 November 2021 (https://www.iana.org/help/licensing-terms), CC0 1.0. Quoted text: RFC 9110, https://www.rfc-editor.org/rfc/rfc9110, “Copyright (c) 2022 IETF Trust and the persons identified as the document authors. All rights reserved.”, subject to BCP 78 and the Trust Legal Provisions (https://trustee.ietf.org/documents/trust-legal-provisions/, TLP 5.0). The poster quotes about 1,700 of the roughly 69,000 words of RFC 9110, less than one fifth, so condition (y) of Section 3.c.iii (the legends) does not apply; the footer still attributes the text to the IETF, names RFC 9110 and gives its copyright line. RFC 9110 carries the pre-5378 legend, which forbids modifying the document outside the IETF Standards Process: every quoted portion is unmodified.

The status code of a response is a three-digit integer code that describes the result of the request and the semantics of the response, including whether the request was successful and what content is enclosed (if any). All valid status codes are within the range of 100 to 599, inclusive.

The first digit of the status code defines the class of response. The last two digits do not have any categorization role. There are five values for the first digit:

  • 1xx (Informational): The request was received, continuing process
  • 2xx (Successful): The request was successfully received, understood, and accepted
  • 3xx (Redirection): Further action needs to be taken in order to complete the request
  • 4xx (Client Error): The request contains bad syntax or cannot be fulfilled
  • 5xx (Server Error): The server failed to fulfill an apparently valid request

HTTP status codes are extensible. A client is not required to understand the meaning of all registered status codes, though such understanding is obviously desirable. However, a client MUST understand the class of any status code, as indicated by the first digit, and treat an unrecognized status code as being equivalent to the x00 status code of that class.

The status codes listed below are defined in this specification. The reason phrases listed here are only recommendations -- they can be replaced by local equivalents or left out altogether without affecting the protocol.

Informational 1xx#

The 1xx (Informational) class of status code indicates an interim response for communicating connection status or request progress prior to completing the requested action and sending a final response.

100 Continue 15.2.1The 100 (Continue) status code indicates that the initial part of a request has been received and has not yet been rejected by the server.
101 Switching Protocols 15.2.2The 101 (Switching Protocols) status code indicates that the server understands and is willing to comply with the client's request, via the Upgrade header field (Section 7.8), for a change in the application protocol being used on this connection.
102 Processing RFC 2518
103 Early Hints RFC 8297
104 Upload Resumption Supported draft-ietf-httpbis-resumable-upload-05TEMPORARY - registered 2024-11-13, extension registered 2025-09-15, expires 2026-11-13
105-199 Unassigned

Successful 2xx#

The 2xx (Successful) class of status code indicates that the client's request was successfully received, understood, and accepted.

200 OK 15.3.1The 200 (OK) status code indicates that the request has succeeded.
201 Created 15.3.2The 201 (Created) status code indicates that the request has been fulfilled and has resulted in one or more new resources being created.
202 Accepted 15.3.3The 202 (Accepted) status code indicates that the request has been accepted for processing, but the processing has not been completed.
203 Non-Authoritative Information 15.3.4The 203 (Non-Authoritative Information) status code indicates that the request was successful but the enclosed content has been modified from that of the origin server's 200 (OK) response by a transforming proxy (Section 7.7).
204 No Content 15.3.5The 204 (No Content) status code indicates that the server has successfully fulfilled the request and that there is no additional content to send in the response content.
205 Reset Content 15.3.6The 205 (Reset Content) status code indicates that the server has fulfilled the request and desires that the user agent reset the "document view", which caused the request to be sent, to its original state as received from the origin server.
206 Partial Content 15.3.7The 206 (Partial Content) status code indicates that the server is successfully fulfilling a range request for the target resource by transferring one or more parts of the selected representation.
207 Multi-Status RFC 4918
208 Already Reported RFC 5842
209-225 Unassigned
226 IM Used RFC 3229
227-299 Unassigned

Redirection 3xx#

The 3xx (Redirection) class of status code indicates that further action needs to be taken by the user agent in order to fulfill the request.

300 Multiple Choices 15.4.1The 300 (Multiple Choices) status code indicates that the target resource has more than one representation, each with its own more specific identifier, and information about the alternatives is being provided so that the user (or user agent) can select a preferred representation by redirecting its request to one or more of those identifiers.
301 Moved Permanently 15.4.2The 301 (Moved Permanently) status code indicates that the target resource has been assigned a new permanent URI and any future references to this resource ought to use one of the enclosed URIs.
302 Found 15.4.3The 302 (Found) status code indicates that the target resource resides temporarily under a different URI.
303 See Other 15.4.4The 303 (See Other) status code indicates that the server is redirecting the user agent to a different resource, as indicated by a URI in the Location header field, which is intended to provide an indirect response to the original request.
304 Not Modified 15.4.5The 304 (Not Modified) status code indicates that a conditional GET or HEAD request has been received and would have resulted in a 200 (OK) response if it were not for the fact that the condition evaluated to false.
305 Use Proxy 15.4.6The 305 (Use Proxy) status code was defined in a previous version of this specification and is now deprecated (Appendix B of [RFC7231]).
306 (Unused) 15.4.7The 306 status code was defined in a previous version of this specification, is no longer used, and the code is reserved.
307 Temporary Redirect 15.4.8The 307 (Temporary Redirect) status code indicates that the target resource resides temporarily under a different URI and the user agent MUST NOT change the request method if it performs an automatic redirection to that URI.
308 Permanent Redirect 15.4.9The 308 (Permanent Redirect) status code indicates that the target resource has been assigned a new permanent URI and any future references to this resource ought to use one of the enclosed URIs.
309-399 Unassigned

Client Error 4xx#

The 4xx (Client Error) class of status code indicates that the client seems to have erred.

400 Bad Request 15.5.1The 400 (Bad Request) status code indicates that the server cannot or will not process the request due to something that is perceived to be a client error (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).
401 Unauthorized 15.5.2The 401 (Unauthorized) status code indicates that the request has not been applied because it lacks valid authentication credentials for the target resource.
402 Payment Required 15.5.3The 402 (Payment Required) status code is reserved for future use.
403 Forbidden 15.5.4The 403 (Forbidden) status code indicates that the server understood the request but refuses to fulfill it.
404 Not Found 15.5.5The 404 (Not Found) status code indicates that the origin server did not find a current representation for the target resource or is not willing to disclose that one exists.
405 Method Not Allowed 15.5.6The 405 (Method Not Allowed) status code indicates that the method received in the request-line is known by the origin server but not supported by the target resource.
406 Not Acceptable 15.5.7The 406 (Not Acceptable) status code indicates that the target resource does not have a current representation that would be acceptable to the user agent, according to the proactive negotiation header fields received in the request (Section 12.1), and the server is unwilling to supply a default representation.
407 Proxy Authentication Required 15.5.8The 407 (Proxy Authentication Required) status code is similar to 401 (Unauthorized), but it indicates that the client needs to authenticate itself in order to use a proxy for this request.
408 Request Timeout 15.5.9The 408 (Request Timeout) status code indicates that the server did not receive a complete request message within the time that it was prepared to wait.
409 Conflict 15.5.10The 409 (Conflict) status code indicates that the request could not be completed due to a conflict with the current state of the target resource.
410 Gone 15.5.11The 410 (Gone) status code indicates that access to the target resource is no longer available at the origin server and that this condition is likely to be permanent.
411 Length Required 15.5.12The 411 (Length Required) status code indicates that the server refuses to accept the request without a defined Content-Length (Section 8.6).
412 Precondition Failed 15.5.13The 412 (Precondition Failed) status code indicates that one or more conditions given in the request header fields evaluated to false when tested on the server (Section 13).
413 Content Too Large 15.5.14The 413 (Content Too Large) status code indicates that the server is refusing to process a request because the request content is larger than the server is willing or able to process.
414 URI Too Long 15.5.15The 414 (URI Too Long) status code indicates that the server is refusing to service the request because the target URI is longer than the server is willing to interpret.
415 Unsupported Media Type 15.5.16The 415 (Unsupported Media Type) status code indicates that the origin server is refusing to service the request because the content is in a format not supported by this method on the target resource.
416 Range Not Satisfiable 15.5.17The 416 (Range Not Satisfiable) status code indicates that the set of ranges in the request's Range header field (Section 14.2) has been rejected either because none of the requested ranges are satisfiable or because the client has requested an excessive number of small or overlapping ranges (a potential denial of service attack).
417 Expectation Failed 15.5.18The 417 (Expectation Failed) status code indicates that the expectation given in the request's Expect header field (Section 10.1.1) could not be met by at least one of the inbound servers.
418 (Unused) 15.5.19[RFC2324] was an April 1 RFC that lampooned the various ways HTTP was abused; one such abuse was the definition of an application-specific 418 status code, which has been deployed as a joke often enough for the code to be unusable for any future use.
419-420 Unassigned
421 Misdirected Request 15.5.20The 421 (Misdirected Request) status code indicates that the request was directed at a server that is unable or unwilling to produce an authoritative response for the target URI.
422 Unprocessable Content 15.5.21The 422 (Unprocessable Content) status code indicates that the server understands the content type of the request content (hence a 415 (Unsupported Media Type) status code is inappropriate), and the syntax of the request content is correct, but it was unable to process the contained instructions.
423 Locked RFC 4918
424 Failed Dependency RFC 4918
425 Too Early RFC 8470
426 Upgrade Required 15.5.22The 426 (Upgrade Required) status code indicates that the server refuses to perform the request using the current protocol but might be willing to do so after the client upgrades to a different protocol.
427 Unassigned
428 Precondition Required RFC 6585
429 Too Many Requests RFC 6585
430 Unassigned
431 Request Header Fields Too Large RFC 6585
432-450 Unassigned
451 Unavailable For Legal Reasons RFC 7725
452-499 Unassigned

Server Error 5xx#

The 5xx (Server Error) class of status code indicates that the server is aware that it has erred or is incapable of performing the requested method.

500 Internal Server Error 15.6.1The 500 (Internal Server Error) status code indicates that the server encountered an unexpected condition that prevented it from fulfilling the request.
501 Not Implemented 15.6.2The 501 (Not Implemented) status code indicates that the server does not support the functionality required to fulfill the request.
502 Bad Gateway 15.6.3The 502 (Bad Gateway) status code indicates that the server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while attempting to fulfill the request.
503 Service Unavailable 15.6.4The 503 (Service Unavailable) status code indicates that the server is currently unable to handle the request due to a temporary overload or scheduled maintenance, which will likely be alleviated after some delay.
504 Gateway Timeout 15.6.5The 504 (Gateway Timeout) status code indicates that the server, while acting as a gateway or proxy, did not receive a timely response from an upstream server it needed to access in order to complete the request.
505 HTTP Version Not Supported 15.6.6The 505 (HTTP Version Not Supported) status code indicates that the server does not support, or refuses to support, the major version of HTTP that was used in the request message.
506 Variant Also Negotiates RFC 2295
507 Insufficient Storage RFC 4918
508 Loop Detected RFC 5842
509 Unassigned
510 Not Extended RFC 2774 · Status change of HTTP experiments to HistoricOBSOLETED
511 Network Authentication Required RFC 6585
512-599 Unassigned