HTTP Status Code Reference

Overview

# HTTP Status Code Reference

HTTP status codes are three-digit responses sent by a web server to indicate the result of an HTTP request. They help browsers, applications, developers, and API clients understand whether a request was successful, redirected, or encountered an error.

1xx Informational Status Codes

1xx status codes provide informational responses while a request is being processed.

- 100 Continue — The server has received the initial request headers and expects the client to continue. - 101 Switching Protocols — The server agrees to switch to a different protocol.

2xx Success Status Codes

2xx status codes indicate that a request was successfully received and processed.

- 200 OK — The request was successful. - 201 Created — A new resource was successfully created. - 202 Accepted — The request has been accepted for processing but may not be completed yet. - 204 No Content — The request was successful but there is no response content.

3xx Redirection Status Codes

3xx status codes indicate that additional action or a different resource location may be required.

- 301 Moved Permanently — The resource has permanently moved to a new URL. - 302 Found — The resource is temporarily available at another URL. - 304 Not Modified — The cached version of the resource can be used. - 307 Temporary Redirect — The request should temporarily use another URL while preserving the HTTP method. - 308 Permanent Redirect — The resource has permanently moved while preserving the HTTP method.

4xx Client Error Status Codes

4xx status codes indicate that there is an issue with the request from the client.

- 400 Bad Request — The server cannot process the request because it is invalid. - 401 Unauthorized — Authentication is required or has failed. - 403 Forbidden — The server understood the request but refuses to authorize it. - 404 Not Found — The requested resource could not be found. - 405 Method Not Allowed — The HTTP method is not supported for the requested resource. - 408 Request Timeout — The server timed out while waiting for the request. - 409 Conflict — The request conflicts with the current state of the resource. - 429 Too Many Requests — The client has sent too many requests within a given period.

5xx Server Error Status Codes

5xx status codes indicate that the server encountered an error while processing a valid request.

- 500 Internal Server Error — A generic server-side error occurred. - 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 an upstream server. - 503 Service Unavailable — The server is temporarily unable to handle the request. - 504 Gateway Timeout — A gateway or proxy did not receive a timely response from an upstream server.

Why HTTP Status Codes Matter

HTTP status codes are useful when developing websites, APIs, and web applications. They help developers diagnose broken links, authentication problems, redirects, rate limits, server failures, and other HTTP-related issues.

Conclusion

This HTTP Status Code Reference provides a quick overview of commonly encountered HTTP response codes. Developers can use it as a convenient reference when building, testing, and troubleshooting websites and APIs.