Some specific HTTP status codes
 

200 OK: Successful request
400 Bad Request: Invalid argument (invalid request payload)
403 Forbidden: Permission denied (e.g. invalid API key)
429 Resource Exhausted: Either out of resource quota or reaching rate limiting
500 Internal Server Error: Internal server error (retry your request)
503 Service Unavailable: Unavailable
504 Gateway Timeout: Deadline exceeded (retry your request)
600 Busy: The server is temporarily unable to handle the request due to a high volume of requests