200 OK This response code indicates that the request was successful.
201 Created This indicates the request was successful and a resource was created. It is used to confirm success of a PUT or POST request.
400 Bad Requests The request was malformed. This happens especially with POST and PUT requests, when the data does not pass validation, or is in the wrong format.
404 Not Found This response indicates that the required resource could not be found. This is generally returned to all requests which point to a URL with no corresponding resource.
401 Unauthorized. This error indicates that you need to perform authentication before accessing the resource.
405 Method Not Allowed The HTTP method used is not supported for this resource.
409 Conflicts This indicates a conflict. For instance, you are using a PUT request to create the same resource twice.
500 Internal Server Errors When all else fails; generally, a 500 response is used when processing fails due to unanticipated circumstances on the server side, which causes the server to error out.