| 100 | Continue | The initial part of the request was received; the client should continue sending the rest. |
| 101 | Switching Protocols | The server agrees to switch protocols as requested (e.g. to WebSocket). |
| 102 | Processing | The server has received the request and is processing it, but no response is available yet (WebDAV). |
| 103 | Early Hints | Preliminary headers sent before the final response, letting the client preload resources. |
| 200 | OK | The request succeeded and the response body contains the requested resource. |
| 201 | Created | The request succeeded and a new resource was created as a result. |
| 202 | Accepted | The request was accepted for processing, but processing is not complete. |
| 203 | Non-Authoritative Information | The returned metadata is from a proxy or cache, not the origin server. |
| 204 | No Content | The request succeeded but there is no content to send back. |
| 205 | Reset Content | The request succeeded; the client should reset the document view that sent it. |
| 206 | Partial Content | The server is delivering only part of the resource due to a Range header. |
| 226 | IM Used | The server fulfilled the request using one or more instance manipulations. |
| 300 | Multiple Choices | The request has more than one possible response; the client should choose one. |
| 301 | Moved Permanently | The resource has been permanently moved to a new URL given in the response. |
| 302 | Found | The resource temporarily resides at a different URL; the original URL should keep being used. |
| 303 | See Other | The response to the request can be found at another URL using a GET request. |
| 304 | Not Modified | The cached version of the resource is still valid; no body is sent. |
| 305 | Use Proxy | The requested resource must be accessed through the given proxy (deprecated, security concerns). |
| 307 | Temporary Redirect | The resource temporarily resides at a different URL; the request method must not change. |
| 308 | Permanent Redirect | The resource has permanently moved; the request method must not change. |
| 400 | Bad Request | The server cannot process the request due to malformed syntax or invalid data. |
| 401 | Unauthorized | Authentication is required and has either failed or not been provided. |
| 402 | Payment Required | Reserved for future use; occasionally used for API rate/paywall limits. |
| 403 | Forbidden | The server understood the request but refuses to authorize it. |
| 404 | Not Found | The server cannot find the requested resource. |
| 405 | Method Not Allowed | The request method is known but not supported by the target resource. |
| 406 | Not Acceptable | No content matching the criteria given in the request headers is available. |
| 407 | Proxy Authentication Required | The client must authenticate itself with a proxy first. |
| 408 | Request Timeout | The server timed out waiting for the request. |
| 409 | Conflict | The request conflicts with the current state of the target resource. |
| 410 | Gone | The resource is permanently gone and no forwarding address is known. |
| 411 | Length Required | The server requires a Content-Length header that was not supplied. |
| 412 | Precondition Failed | A precondition in the request headers evaluated to false. |
| 413 | Payload Too Large | The request body is larger than the server is willing to process. |
| 414 | URI Too Long | The request URI is longer than the server is willing to interpret. |
| 415 | Unsupported Media Type | The request payload format is not supported by the server. |
| 416 | Range Not Satisfiable | The Range header's value cannot be satisfied by the resource. |
| 417 | Expectation Failed | The server cannot meet the requirements of the Expect header. |
| 418 | I'm a Teapot | An April Fools joke from RFC 2324; some servers use it deliberately. |
| 421 | Misdirected Request | The request was routed to a server that cannot produce a response for the target authority. |
| 422 | Unprocessable Entity | The request is well-formed but contains semantic errors. |
| 423 | Locked | The resource being accessed is locked (WebDAV). |
| 424 | Failed Dependency | The request failed because a previous, related request failed (WebDAV). |
| 425 | Too Early | The server is unwilling to process a request that might be replayed. |
| 426 | Upgrade Required | The client should switch to a different protocol given in the Upgrade header. |
| 428 | Precondition Required | The server requires the request to be conditional. |
| 429 | Too Many Requests | The client has sent too many requests in a given time frame (rate limiting). |
| 431 | Request Header Fields Too Large | The request headers are too large for the server to process. |
| 451 | Unavailable For Legal Reasons | The resource is unavailable due to a legal demand (e.g. censorship). |
| 500 | Internal Server Error | A generic error indicating the server encountered an unexpected condition. |
| 501 | Not Implemented | The server does not support the functionality required to fulfill the request. |
| 502 | Bad Gateway | A gateway or proxy server received an invalid response from the upstream server. |
| 503 | Service Unavailable | The server is temporarily unable to handle the request (overload or maintenance). |
| 504 | Gateway Timeout | A gateway or proxy server did not get a timely response from the upstream server. |
| 505 | HTTP Version Not Supported | The server does not support the HTTP protocol version used in the request. |
| 506 | Variant Also Negotiates | The server has an internal content-negotiation configuration error. |
| 507 | Insufficient Storage | The server cannot store the representation needed to complete the request (WebDAV). |
| 508 | Loop Detected | The server detected an infinite loop while processing the request (WebDAV). |
| 510 | Not Extended | Further extensions to the request are required for the server to fulfill it. |
| 511 | Network Authentication Required | The client needs to authenticate to gain network access (e.g. captive portal). |