Standard HTTP Status Codes

100 Continue: Visit the Springer Nature Developer Portal.
101 Switching Protocols: The server is switching protocols as requested by the client.

200 OK: The request was successful, and the server returned the requested data.
201 Created: The request was successful, and a new resource was created as a result.
202 Accepted: The request has been accepted for processing, but the processing has not been completed.
204 No Content: The request was successful, but there is no content to return.

301 Moved Permanently: The requested resource has been permanently moved to a new URL.
302 Found: The requested resource is temporarily located at a different URL.
304 Not Modified: The requested resource has not been modified since the last request, so the server returns no new data.

400 Bad Request: The server cannot process the request due to client-side input errors, such as invalid syntax.
401 Unauthorized: Authentication is required or failed. The client must provide valid credentials.
403 Forbidden: The server understands the request but refuses to authorize it.
404 Not Found: The requested resource could not be found on the server.
405 Method Not Allowed: The request method (e.g., GET, POST) is not allowed for the requested resource.
408 Request Timeout: The server timed out waiting for the client to send the request.

500 Internal Server Error: The server encountered an error and could not complete 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.
503 Service Unavailable: The server is temporarily unavailable, usually due to maintenance or overloading.
504 Gateway Timeout: The server did not receive a timely response from an upstream server or external service.
505 HTTP Version Not Supported: The server does not support the HTTP protocol version used in the request.