Shipup API uses standard HTTP response codes. Here is an exhaustive list of all the response codes possibly return by the API.
Standard response for successful HTTP request
The request has been fulfilled, resulting in the creation of a new resource
The request has been accepted for processing, but the processing has not been completed
The server cannot or will not process the request due to an apparent client error (invalid request payload for example)
The request is missing authentication. It is more likely that the API key is missing in request header or is invalid
The request cannot be processed due to end of trial period (default 14 days upon account creation) or because the paying feature you are trying to access is not enabled for your account.
Attempt to access to a resource with unnecessary permissions. If you have multiple accounts, you may retry the request with another API key
Rate limiting exceeded. See Rate Limiting section for details
The server has encountered an unexpected error
The server is under maintenance. Only Shipup tracking page is accessible