How can I create an unassigned ticket via API? I've tried creating a ticket with the responder_id field set to null but that's returning a datatype_mismatch error. In your examples for create ticket I don't see any references to responder_id. Is this because it's something that each domain sets up individually?
The 'responder_id' field refers to the agent to whom the ticket would be attributed to. Please check if the field is made mandatory under Admin -> Ticket fields section as it expects an input value. You can refer to the documentation here to understand more about the field types -> https://developer.freshdesk.com/api/#create_ticket