HTTP Status Codes — best

Continue

Server received request headers, client should proceed to send the body.

Switching Protocols

Server agrees to switch protocols per the client's Upgrade header.

OK

Request succeeded. The response body contains the result.

Created

Request succeeded and a new resource was created.

No Content

Request succeeded but no response body.

Partial Content

Partial resource returned (range requests).

Moved Permanently

Resource permanently moved to a new URL.

Found

Resource temporarily at a different URL.

Not Modified

Cached resource is still valid. Client should use cache.

Temporary Redirect

Redirect with same HTTP method.

Permanent Redirect

Permanent redirect preserving the HTTP method.

Bad Request

Server cannot process the request due to client error.

Unauthorized

Authentication required. Client must authenticate first.

Forbidden

Server understood request but refuses to authorize it.

Not Found

Resource not found at the given URL.

Method Not Allowed

HTTP method is not allowed for this resource.

Request Timeout

Server timed out waiting for request from client.

Conflict

Request conflicts with current state of the resource.

Gone

Resource permanently deleted and will not be available again.

Payload Too Large

Request body exceeds server's size limits.

URI Too Long

Request URI is too long for the server to process.

Unsupported Media Type

Request media type is not supported by the server.

Unprocessable Entity

Request is well-formed but contains semantic errors.

Too Many Requests

Client has sent too many requests (rate limiting).

Internal Server Error

Server encountered an unexpected condition.

Not Implemented

Server does not support the requested functionality.

Bad Gateway

Upstream server returned an invalid response.

Service Unavailable

Server temporarily unavailable (overloaded or down).

Gateway Timeout

Upstream server failed to respond in time.