HTTP status codes

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

The server is switching protocols as requested by the client via the Upgrade header.

The server has received and is processing the request, but no response is available yet (WebDAV).

Used to return some response headers before the final HTTP message, e.g. to preload resources.

The request succeeded. The meaning depends on the HTTP method used.

The request succeeded and a new resource was created as a result.

The request has been accepted for processing, but the processing is not complete.

The server successfully processed the request and is not returning any content.

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

The resource has permanently moved to a new URL. Search engines update their links; passes SEO value.

The resource is temporarily at a different URL. The original URL should keep being used.

The response can be found at another URL using a GET request — often after a POST.

The cached version of the requested resource is still valid; the client can reuse it.

Like 302, but the request method must not change when following the redirect.

Like 301, but the request method must not change when following the redirect.

The server cannot process the request due to a client error (malformed syntax, invalid framing).

Authentication is required and has failed or not been provided.

The server understood the request but refuses to authorise it. Authentication won't help.

The server cannot find the requested resource. The most common error on the web.

The request method is known by the server but not supported by the target resource.

The server timed out waiting for the request.

The request conflicts with the current state of the server, e.g. an edit conflict.

The resource is permanently gone and no forwarding address is known.

An April Fools' joke from RFC 2324 — the server refuses to brew coffee because it is a teapot.

The request was well-formed but contains semantic errors (common in APIs for validation failures).

The user has sent too many requests in a given amount of time (rate limiting).

A generic error message when the server encounters an unexpected condition.

The server does not support the functionality required to fulfil the request.

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

The server is not ready to handle the request — often overloaded or down for maintenance.

A gateway server did not receive a timely response from the upstream server.

The client needs to authenticate to gain network access, e.g. a captive portal.