How can I send confirmed order details to an API using a custom shipping service?

[hummy123]

Hi there.

This is my first time using Shopify. I’m trying to create an app that adds a shipping service on the checkout page (can do that fine using the CarrierService API ) and, when/if the customer checks out while my shipping service is selected, sends order details to an API (so I can then email those details to the carrier for them to fulfil the order).

The first part is fine, but the second part I am stuck on. I would appreciate any assistance here.

I understand the callback URL for the CarrierService API already receives order details, but those order details are tentative (the customer may change their mind) so I can’t use them for what I want (which is to send an email for a placed/confirmed order).