We summarize the possible Rosette Cloud error codes in our documentation, but there could be multiple reasons why you're seeing a 403. A 403 occurs when Rosette has validated your API key to your account, but the status of your account or plan does not allow successful calls to Rosette at that time. The most likely cause is that you've hit your call limit for your allotted time, and all subsequent calls will return 403s until your call limit refreshes. If you believe you shouldn't be seeing a 403, please don't hesitate to contact us.