HTTP Response Codes

HTTP Response Codes are three-digit status codes returned by a web server in response to an HTTP request. They indicate whether the request was successful or encountered issues. These codes are categorized into five classes:

Code Range	Category	Description
1xx	Informational	Used to indicate a server is changing protocols, such as HTTP to WebSocket
2xx	Success	Indicating that the request has been understood correctly
3xx	Redirection	Signifying that further action is required to complete the request, such as redirecting to a new URL
4xx	Client Error	Indicates that the request contains incorrect or inaccurate information
5xx	Server Error	Indicates that the request has encountered an issue processing the request

Listed below are some of the most common ones to see:

• 200 OK: The request has succeeded. This is the standard response for successful HTTP request.

• 201 Created: The request has been fullfilled, resulting in the creation of a new resource.

• 204 No Content: The server successfully processed the request, but there is no content to send in the response.

• 206 Partial Content: The server is delivering only part of the resource due to a range header sent by the client.

• 301 Moved Permanently: The requested resource has been permanently moved to a new URL.

• 302 Found: The requested resource resides temporarily at a different URL.

• 400 Bad Request: The server could not understand the request due to invalid syntax.

• 401 Unauthorized: The client must authenticate itself to get the requested response (usually requires login).

• 403 Forbidden: The server understands the request but refuses to authorize it.

• 404 Not Found: The server cannot find the requested resource (often returned when the URL is incorrect).

• 405 Method Not Allowed: The request method is known by the server but is not supported for the resource.

• 429 Too Many Requests: The user has sent too many requests in a given amount of time ("rate limiting")

• 500 Internal Server Error: The server encountered an unexpected condition that prevented it from fulfilling the request.

• 501 Not Implemented: The server does not support the functionality required to fulfill the request.

• 502 Bad Gateway: The server received an invalid response from an upstream server while acting as a gateway.

• 503 Service Unavailable: The server is not ready to handle the request. Common causes are server overload or maintenance.

• 504 Gateway Timeout: The server, while acting as a gateway, did not receive a timely response from an upstream server.

• 505 HTTP Version Not Supported: The server does not support the HTTP protocol version used in the request.