HTTP Codes List
HTTP status codes are three-digit responses sent by a server in response to a client request, most often from a web browser. They inform whether the request was successful, requires redirection, or if a user-side or server-side error occurred.
Each HTTP code belongs to one of five categories: informational (1xx), success (2xx), redirection (3xx), client errors (4xx), and server errors (5xx). Thanks to these codes, browsers, search engine robots, and web applications can correctly interpret server responses and react accordingly.
Knowledge of HTTP codes is particularly important for developers, server administrators, and SEO specialists analyzing website performance. Below you will find a complete list of the most important HTTP status codes along with a description of their meaning and application.
Informational
| Code | Name | Description |
|---|---|---|
| 100 | Continue | Server received request headers, client can continue sending content. |
| 101 | Switching Protocols | Server is switching protocols according to the client's request (e.g., WebSocket). |
| 103 | Early Hints | Interim response with headers before the server sends the actual response. |
Success
| Code | Name | Description |
|---|---|---|
| 200 | OK | The request was successful. |
| 201 | Created | Resource successfully created. |
| 202 | Accepted | Request accepted but not yet processed. |
| 204 | No Content | Success, but response contains no content. |
| 206 | Partial Content | Server returns only part of the resource (e.g., for file downloads). |
Redirects
| Code | Name | Description |
|---|---|---|
| 301 | Moved Permanently | Resource permanently moved to a new address. |
| 302 | Found | Resource temporarily available at a different address. |
| 303 | See Other | Response to the request is available under a different URI (GET). |
| 304 | Not Modified | Resource has not changed since the last request — use cache. |
| 307 | Temporary Redirect | Temporary redirect preserving the HTTP method. |
| 308 | Permanent Redirect | Permanent redirect preserving the HTTP method. |
Client Errors
| Code | Name | Description |
|---|---|---|
| 400 | Bad Request | Server cannot process the request due to a client-side error. |
| 401 | Unauthorized | Authentication required. |
| 403 | Forbidden | No permission for the resource. |
| 404 | Not Found | Resource does not exist. |
| 405 | Method Not Allowed | HTTP method not allowed for this resource. |
| 408 | Request Timeout | Client timed out while sending the request. |
| 409 | Conflict | Conflict with the current state of the resource. |
| 410 | Gone | Resource permanently removed. |
| 413 | Content Too Large | Request content exceeds server limit. |
| 414 | URI Too Long | URL address is too long. |
| 415 | Unsupported Media Type | Server does not support the data format. |
| 418 | I'm a teapot | Joke: the server refuses to brew coffee because it is a teapot |
| 422 | Unprocessable Entity | Request is syntactically correct but impossible to process. |
| 429 | Too Many Requests | Request limit exceeded (rate limiting). |
| 444 | No Response | The server decided not to respond to the client. |
| 499 | Client Closed Request | The client (e.g., browser) closed the connection before the server could send a response |
Server Errors
| Code | Name | Description |
|---|---|---|
| 500 | Internal Server Error | General server error. |
| 501 | Not Implemented | Server does not support the requested functionality. |
| 502 | Bad Gateway | Proxy server received an invalid response. |
| 503 | Service Unavailable | Server temporarily unavailable. |
| 504 | Gateway Timeout | Proxy server received an invalid response. |
| 505 | HTTP Version Not Supported | The server does not support the HTTP protocol version used in the request. |
Most common HTTP errors
Some HTTP status codes appear much more often than others and are well known to internet users. They most often concern page availability issues, server configuration errors, or invalid URLs.
404 Not Found
A 404 error means the server is working correctly but cannot find the resource at the specified URL. It most often appears when a page has been deleted, the address is wrong, or a link leads to a non-existent subpage.
500 Internal Server Error
Code 500 signifies a general server error. It occurs when an application or server configuration encounters an unexpected problem and is unable to handle the request properly.
502 Bad Gateway
A 502 error appears when a server acting as a gateway or proxy receives an invalid response from an upstream server. It often occurs in architectures with load balancers or reverse proxies.
503 Service Unavailable
Code 503 means the server is temporarily unavailable. This is most often due to server overload, maintenance work, or resource limits.
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