| Status | Description | RFC(s) |
| 000 | Used mostly with UDP traffic. | N/A |
| | Informational |
| 100 | Continue | 2616 |
| 101 | Switching Protocols | 2616 |
| 102 | Processing | 2518 |
| | Successful Transaction |
| 200 | OK | 1945, 2616 |
| 201 | Created | 1945, 2616 |
| 202 | Accepted | 1945, 2616 |
| 203 | Non-Authoritative Information | 2616 |
| 204 | No Content | 1945, 2616, 4918 |
| 205 | Reset Content | 2616 |
| 206 | Partial Content | 2616 |
| 207 | Multi Status | 2518, 4918 |
| | Redirection |
| 300 | Multiple Choices | 1945, 2616, 4918 |
| 301 | Moved Permanently | 1945, 2616, 4918 |
| 302 | Moved Temporarily | 1945, 2616, 4918 |
| 303 | See Other | 2616, 4918 |
| 304 | Not Modified | 1945, 2616 |
| 305 | Use Proxy | 2616, 4918 |
| 307 | Temporary Redirect | 2616, 4918 |
| | Client Error |
| 400 | Bad Request | 1945, 2616, 4918 |
| 401 | Unauthorized | 1945, 2616 |
| 402 | Payment Required | 2616 |
| 403 | Forbidden | 1945, 2616, 4918 |
| 404 | Not Found | 1945, 2616 |
| 405 | Method Not Allowed | 2616 |
| 406 | Not Acceptable | 2616 |
| 407 | Proxy Authentication Required | 2616 |
| 408 | Request Timeout | 2616 |
| 409 | Conflict | 2616, 4918 |
| 410 | Gone | 2616 |
| 411 | Length Required | 2616 |
| 412 | Precondition Failed | 2616, 4918 |
| 413 | Request Entity Too Large | 2616 |
| 414 | Request URI Too Large | 2616, 4918 |
| 415 | Unsupported Media Type | 2616 |
| 416 | Request Range Not Satisfiable | 2616 |
| 417 | Expectation Failed | 2616 |
| 422 | Unprocessable Entity | 2518, 4918 |
| 424 | Locked | (broken WebDAV implementations??) |
| 424 | Failed Dependency | 2518, 4918 |
| 433 | Unprocessable Entity | |
| | Server Errors |
| 500 | Internal Server Error | 1945, 2616 |
| 501 | Not Implemented | 1945, 2616 |
| 502 | Bad Gateway | 1945, 2616 |
| 503 | Service Unavailable | 1945, 2616 |
| 504 | Gateway Timeout | 2616 |
| 505 | HTTP Version Not Supported | 2616 |
| 507 | Insufficient Storage | 2518, 4918 |
| | Broken Server Software |
| 600 | Squid: header parsing error | |
| 601 | Squid: header size overflow detected while parsing | |
| 601 | roundcube: software configuration error | |
| 603 | roundcube: invalid authorization | |