100ContinueInformational (1xx)
The server has received the headers and the client may continue sending the request body.
101Switching ProtocolsInformational (1xx)
The server agrees to switch protocols, as requested by the client (e.g., to WebSocket).
200OKSuccess (2xx)
The request has succeeded.
201CreatedSuccess (2xx)
The request succeeded and a new resource was created.
202AcceptedSuccess (2xx)
The request has been accepted for processing, but processing isn't complete.
204No ContentSuccess (2xx)
The request succeeded, but there's no content to return.
206Partial ContentSuccess (2xx)
The server is returning only part of the resource, per the range requested by the client.
301Moved PermanentlyRedirection (3xx)
The resource has been permanently moved to a new URL.
302FoundRedirection (3xx)
The resource is temporarily at a different URL.
304Not ModifiedRedirection (3xx)
The resource hasn't changed since it was last requested (used with caching).
307Temporary RedirectRedirection (3xx)
A temporary redirect that, unlike 302, requires keeping the same HTTP method on the new request.
308Permanent RedirectRedirection (3xx)
A permanent redirect that, unlike 301, requires keeping the same HTTP method.
400Bad RequestClient error (4xx)
The server can't process the request due to a client syntax or format error.
401UnauthorizedClient error (4xx)
The request requires authentication, which wasn't provided or is invalid.
403ForbiddenClient error (4xx)
The server understands the request but refuses to authorize it.
404Not FoundClient error (4xx)
The server can't find the requested resource.
405Method Not AllowedClient error (4xx)
The HTTP method used isn't allowed for this resource.
408Request TimeoutClient error (4xx)
The server timed out waiting for the client to send the complete request.
409ConflictClient error (4xx)
The request conflicts with the current state of the resource on the server.
410GoneClient error (4xx)
The requested resource is no longer available and won't be again.
418I'm a teapotClient error (4xx)
A joke code from the April Fools' RFC 2324: the server is a teapot and refuses to brew coffee.
422Unprocessable ContentClient error (4xx)
The request is well-formed, but contains semantic errors that prevent it from being processed.
429Too Many RequestsClient error (4xx)
The client has sent too many requests in a given period of time (rate limiting).
500Internal Server ErrorServer error (5xx)
The server has encountered a situation it doesn't know how to handle.
501Not ImplementedServer error (5xx)
The server doesn't recognize the request method or can't fulfill it.
502Bad GatewayServer error (5xx)
The server, acting as a gateway, received an invalid response from the upstream server.
503Service UnavailableServer error (5xx)
The server isn't ready to handle the request, usually due to overload or maintenance.
504Gateway TimeoutServer error (5xx)
The server, acting as a gateway, didn't get a timely response from the upstream server.