Input
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How to use
- Search by status number, name or explanation.
- Filter a code family or common codes and select an entry.
- Copy the code or its direct link, or download the JSON reference.
Interpreting an HTTP response status
The status code summarizes how a server handled an HTTP request. Its first digit identifies the response family, while the specific code gives a more precise meaning.
Use the reference to distinguish protocol meanings from an application’s error message. Diagnosing a failure can also require the response headers, body and server context.
Finding a response code
Search can match the number, protocol name or explanation. The family filters separate informational, successful, redirect, client-error and server-error responses.
Common codes is a browsing shortcut rather than a separate standard. An unassigned number may still appear in a particular product without being a registered status.
404404 Not FoundExample data only. Values, authentication and endpoint behavior must be checked in your own context.
Registration and context
The reference follows the IANA registry snapshot dated October 22, 2026. Reserved, deprecated, obsolete and temporary entries are labeled; check the linked registry when current registration status matters.
HTTP status reference
Copy link creates an address for the selected code. Download JSON exports the full reference, including names, registration states and explanations, rather than only the active filter results.
| Code | Name | Meaning |
|---|---|---|
| 100 | Continue | The server has accepted the initial headers; the client may continue sending the request body. |
| 101 | Switching Protocols | The server agrees to switch to the protocol requested by the client. |
| 102 | Processing | An interim WebDAV response indicating that processing is still in progress. |
| 103 | Early Hints | An interim response containing hints such as resources the client can preload. |
| 104 | Upload Resumption Supported | A temporary registration for resumable uploads. Its current registration expires November 13, 2026. |
| 200 | OK | The request succeeded; the meaning of its response content depends on the request method. |
| 201 | Created | The request created one or more resources. A Location header may identify the primary resource. |
| 202 | Accepted | The request was accepted for processing, but its work has not necessarily finished. |
| 203 | Non-Authoritative Information | A transforming intermediary modified the origin server’s successful response. |
| 204 | No Content | The request succeeded and has no response content. Do not expect a JSON body. |
| 205 | Reset Content | The request succeeded and asks the client to reset the view that produced it. |
| 206 | Partial Content | The server returned one or more requested byte ranges rather than the complete representation. |
| 207 | Multi-Status | A WebDAV response carrying separate outcomes for multiple operations or resources. |
| 208 | Already Reported | A WebDAV binding was already listed earlier in the same multi-status response. |
| 226 | IM Used | The server applied instance manipulations, such as a delta, to the representation. |
| 300 | Multiple Choices | More than one representation is available; the client may need to choose one. |
| 301 | Moved Permanently | The resource has a new permanent URI. Some clients change POST to GET when following it. |
| 302 | Found | The resource is temporarily available elsewhere. Some clients change POST to GET. |
| 303 | See Other | Retrieve the result from another URI, normally using GET; this commonly follows a POST. |
| 304 | Not Modified | A conditional retrieval found no new representation. Reuse the cached response. |
| 305 | Use Proxy | A deprecated instruction to access the resource through a proxy. It should not be used in new APIs. |
| 306 | Unused | This code is unused and reserved; it has no current redirect behavior. |
| 307 | Temporary Redirect | Follow a temporary redirect while preserving the request method and body. |
| 308 | Permanent Redirect | Follow a permanent redirect while preserving the request method and body. |
| 400 | Bad Request | The server cannot process the request because of a client-side problem, such as malformed syntax. |
| 401 | Unauthorized | Valid authentication credentials are required. Check the WWW-Authenticate challenge and your credentials. |
| 402 | Payment Required | Reserved for future use. Payment-related interpretations are specific to the API using it. |
| 403 | Forbidden | The server understood the request but refuses to fulfill it; authentication alone may not resolve it. |
| 404 | Not Found | The resource was not found, or the server does not wish to disclose that it exists. |
| 405 | Method Not Allowed | This method is not allowed for the resource. Check the Allow response header. |
| 406 | Not Acceptable | No available representation satisfies the request’s content-negotiation preferences. |
| 407 | Proxy Authentication Required | Authentication is required by an intermediary proxy rather than the origin server. |
| 408 | Request Timeout | The server did not receive the complete request within the time it was willing to wait. |
| 409 | Conflict | The request conflicts with the current resource state. Resolve the conflict before retrying. |
| 410 | Gone | The resource is no longer available and the condition is likely permanent. |
| 411 | Length Required | The server requires a defined Content-Length for this request. |
| 412 | Precondition Failed | A condition supplied by the client, such as If-Match, evaluated to false. |
| 413 | Content Too Large | The request content is larger than the server is willing or able to process. |
| 414 | URI Too Long | The request URI is longer than the server is willing to interpret. |
| 415 | Unsupported Media Type | The request content format or content encoding is unsupported for this operation. |
| 416 | Range Not Satisfiable | The requested ranges cannot be satisfied for the selected representation. |
| 417 | Expectation Failed | The server cannot meet the expectation given in the Expect request header. |
| 418 | Unused (I’m a teapot) | Reserved as unused in the current HTTP specification; historically known as “I’m a teapot”. |
| 421 | Misdirected Request | The request was sent to a server that cannot provide an authoritative response for this origin. |
| 422 | Unprocessable Content | The content type and syntax are understood, but the contained instructions cannot be processed. |
| 423 | Locked | A WebDAV resource needed by the operation is locked. |
| 424 | Failed Dependency | A WebDAV operation failed because another operation it depended on failed. |
| 425 | Too Early | The server will not risk processing a request that could be replayed from TLS early data. |
| 426 | Upgrade Required | The client must switch protocols before this request can succeed. Check the Upgrade header. |
| 428 | Precondition Required | The server requires a conditional request to help prevent lost updates. |
| 429 | Too Many Requests | The client has sent too many requests. Follow any Retry-After guidance and the API’s rate limits. |
| 431 | Request Header Fields Too Large | The request headers are too large, individually or in total. |
| 451 | Unavailable For Legal Reasons | The resource is unavailable because access is blocked for legal reasons. |
| 500 | Internal Server Error | An unexpected server-side condition prevented the request from being fulfilled. |
| 501 | Not Implemented | The server does not support the functionality required to fulfill the request. |
| 502 | Bad Gateway | A gateway or proxy received an invalid response from its upstream server. |
| 503 | Service Unavailable | The service is temporarily unavailable, often due to overload or maintenance. Check Retry-After. |
| 504 | Gateway Timeout | A gateway or proxy did not receive an upstream response in time. |
| 505 | HTTP Version Not Supported | The server does not support the HTTP version used by the request. |
| 506 | Variant Also Negotiates | A server content-negotiation configuration causes a circular choice of variants. |
| 507 | Insufficient Storage | The server cannot store the representation needed to finish the operation. |
| 508 | Loop Detected | A WebDAV operation encountered an infinite loop. |
| 510 | Not Extended | An obsolete HTTP extension-framework code. Do not use it for new APIs. |
| 511 | Network Authentication Required | The client must authenticate to gain network access, commonly through a captive portal. |
Local tools accept up to 1 MiB, URLs up to 64 KiB, and have a 5-second processing limit. API requests support 100 headers and 100 parameter rows, a 1–120 second timeout and up to 5 MiB of received response data. Long text previews are abbreviated. Requests go directly to your chosen endpoint; CORS and browser policy apply.
Frequently asked questions
Are all three-digit codes standardized?
No. Some numbers are unassigned or used by individual products. Usage by a server or proxy does not by itself establish an IANA registration.
What is the difference between 401 and 403?
401 asks for valid authentication and normally includes a WWW-Authenticate challenge. 403 means the server refuses the operation; supplying credentials may not resolve it.
Does a 4xx response always mean a mistake in my code?
No. It describes the request/response situation. Authentication, permissions, routing, rate limits or application rules can also cause a 4xx response.
Can I share one specific status entry?
Yes. Select it and use Copy link. The link includes a status anchor for that code.
Does Download JSON export only my search results?
No. It exports the complete reference, including the localized descriptions.