Cancel an existing shipment and request a label refund from the carrier. The shipment must not have been picked up or entered the carrier network.

When to use: Call this endpoint when you need to void a previously generated label — for example, if the order was cancelled, the address is incorrect, or you need to regenerate the label with different details.

Prerequisites:

• Valid JWT authentication token (Bearer)
• The carrier identifier (e.g., fedex, dhl, ups)
• The tracking number of the shipment to cancel

Key behaviors:

• Returns a confirmation status indicating whether the cancellation was accepted by the carrier
• Refund processing times vary by carrier
• Some carriers only allow cancellation within a limited time window after label generation
• Labels that have already been scanned by the carrier cannot be cancelled