| 100 | Continue | The server received the request headers; the client should proceed. | |
| 101 | Switching Protocols | Server is switching to the protocol specified in the Upgrade header. | |
| 102 | Processing | Server has received and is processing the request (WebDAV). | |
| 103 | Early Hints | Used for preloading resources while final headers are prepared. | |
| 200 | OK | Standard success response. The request succeeded. | |
| 201 | Created | Resource successfully created. Returned after POST. | |
| 202 | Accepted | Request accepted for processing, but processing is not yet complete. | |
| 203 | Non-Authoritative Information | Returned metadata is from a cached copy, not the origin server. | |
| 204 | No Content | Request succeeded but there is no content to return. | |
| 205 | Reset Content | Tells the client to reset the document view. | |
| 206 | Partial Content | Only part of the resource was returned (used with Range header). | |
| 207 | Multi-Status | Multiple status codes in one response (WebDAV). | |
| 208 | Already Reported | Members already enumerated in a previous reply (WebDAV). | |
| 226 | IM Used | Server has fulfilled a GET request with instance manipulations applied. | |
| 300 | Multiple Choices | Multiple possible responses; user or agent should choose one. | |
| 301 | Moved Permanently | Resource permanently moved to a new URL. | |
| 302 | Found | Resource temporarily located at a different URL. | |
| 303 | See Other | Redirect to another URI with GET after POST/PUT/DELETE. | |
| 304 | Not Modified | Cached version is still valid; no body returned. | |
| 307 | Temporary Redirect | Temporary redirect; method and body unchanged. | |
| 308 | Permanent Redirect | Permanent redirect; method and body unchanged. | |
| 400 | Bad Request | Server cannot process the request due to a client error. | |
| 401 | Unauthorized | Authentication required. Credentials missing or invalid. | |
| 402 | Payment Required | Reserved for future use. Sometimes used for paywalls. | |
| 403 | Forbidden | Server refuses to authorize the request. | |
| 404 | Not Found | Requested resource could not be found on the server. | |
| 405 | Method Not Allowed | HTTP method not supported for the requested resource. | |
| 406 | Not Acceptable | Server cannot produce a response matching Accept headers. | |
| 407 | Proxy Authentication Required | Authentication with a proxy server is needed. | |
| 408 | Request Timeout | Server timed out waiting for the request. | |
| 409 | Conflict | Request conflicts with the current state of the resource. | |
| 410 | Gone | Resource has been permanently deleted and will not return. | |
| 411 | Length Required | Content-Length header is required but not provided. | |
| 412 | Precondition Failed | One or more conditions in the request header were false. | |
| 413 | Content Too Large | Request body exceeds the server's limits. | |
| 414 | URI Too Long | The request URI is longer than the server is willing to interpret. | |
| 415 | Unsupported Media Type | The media format of the request data is not supported. | |
| 416 | Range Not Satisfiable | Requested range falls outside the resource size. | |
| 417 | Expectation Failed | Expect header condition could not be met. | |
| 418 | I'm a Teapot | HTCPCP protocol joke. The server refuses to brew coffee. | |
| 421 | Misdirected Request | Request directed to a server unable to produce a response. | |
| 422 | Unprocessable Content | Server understands content but has semantic errors (WebDAV). | |
| 423 | Locked | Resource is locked (WebDAV). | |
| 424 | Failed Dependency | Request failed due to a previous request failure (WebDAV). | |
| 425 | Too Early | Server unwilling to risk processing a request that might be replayed. | |
| 426 | Upgrade Required | Client should switch to a different protocol. | |
| 428 | Precondition Required | Origin server requires the request to be conditional. | |
| 429 | Too Many Requests | User sent too many requests in a given time (rate limiting). | |
| 431 | Request Header Fields Too Large | Server refuses to process overly large header fields. | |
| 451 | Unavailable For Legal Reasons | Resource unavailable due to legal demands (censorship, DMCA, etc.). | |
| 500 | Internal Server Error | Unexpected condition that prevented fulfilling the request. | |
| 501 | Not Implemented | Server does not support the functionality required. | |
| 502 | Bad Gateway | Upstream server sent an invalid response to the gateway. | |
| 503 | Service Unavailable | Server is not ready to handle the request. Overloaded or down for maintenance. | |
| 504 | Gateway Timeout | Upstream server did not respond in time. | |
| 505 | HTTP Version Not Supported | Server does not support the HTTP protocol version used. | |
| 506 | Variant Also Negotiates | Internal configuration error in content negotiation. | |
| 507 | Insufficient Storage | Server is unable to store the representation (WebDAV). | |
| 508 | Loop Detected | Infinite loop detected while processing the request (WebDAV). | |
| 510 | Not Extended | Further extensions to the request are required. | |
| 511 | Network Authentication Required | Client needs to authenticate to gain network access. | |
