Home > @infiniteobjects/shopify-data-manager > AdminTypes > FulfillmentService > callbackUrl
The callback URL that the fulfillment service has registered for requests. The following considerations apply:
<callbackUrl>/fetch_tracking_numbers endpoint to retrieve tracking numbers for orders, if trackingSupport is set to true. - Shopify queries the <callbackUrl>/fetch_stock endpoint to retrieve inventory levels, if inventoryManagement is set to true. - Shopify uses the <callbackUrl>/fulfillment_order_notification endpoint to send [fulfillment and cancellation requests](https://shopify.dev/apps/fulfillment/fulfillment-service-apps/manage-fulfillments#step-2-receive-fulfillment-requests-and-cancellations), if the fulfillment service has opted in to the fulfillment order based workflow for managing fulfillments (fulfillmentOrdersOptIn is set to true).Signature:
callbackUrl?: Maybe<Scalars['URL']['output']>;