HTTP Status Codes

The server has received the request headers and the client should proceed to send the request body.

The server agrees to switch protocols as requested by the client via the Upgrade header.

The server is processing the request but no response is available yet. Used to prevent timeouts.

Allows the server to send preliminary response headers before the final response, used for preloading resources.

The request succeeded. Response body depends on the method: GET returns the resource, POST returns the result.

The request succeeded and a new resource was created. Common response to POST and PUT requests.

The request has been accepted for processing but is not yet complete. Used for async operations.

The request succeeded but there is no content to send in the response body. Common for DELETE requests.

The server is delivering only part of the resource due to a Range header sent by the client.

The resource has been permanently moved to a new URL. Search engines update their index to the new URL.

The resource is temporarily at a different URL. The client should continue using the original URL for future requests.

The resource hasn’t changed since the last request. The client can use its cached version. Saves bandwidth.

The resource is temporarily at another URL but the HTTP method must not change (unlike 302).

Like 301 but the HTTP method must not change. The redirect is permanent.

The server cannot process the request due to malformed syntax, invalid parameters, or a request that’s too large.

Authentication is required and has failed or not been provided. The client must authenticate to get the requested response.

The server understood the request but refuses to authorize it. Unlike 401, re-authenticating won’t help — access is denied.

The server cannot find the requested resource. Often returned when a URL path doesn’t match any known route.

The HTTP method (GET, POST, etc.) is not supported for this resource. The response includes an Allow header listing valid methods.

The server timed out waiting for the client to send the full request. The client may retry.

The request conflicts with the current state of the server. Common with concurrent edit conflicts.

The resource is permanently gone with no forwarding address. More definitive than 404.

An April Fools' joke from 1998 (RFC 2324). The server refuses to brew coffee because it’s a teapot.

The client has sent too many requests in a given time (rate limiting). The Retry-After header indicates when to retry.

A generic server error. Something went wrong on the server side but no more specific information is available.

A server acting as a gateway or proxy received an invalid response from an upstream server.

The server is temporarily unable to handle the request, typically due to maintenance or overload. Usually temporary.

A server acting as a gateway did not receive a response from the upstream server in time.