Xindus's answer:
AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
FedEx - FedEx app features the creation of a large number of national and international shipping labels so you can keep a record of the status of the online package right at your fingertips.
PackageX Receive - PackageX Receive digitizes package-receiving operations and delivers world-class package management solutions.
Delhivery - Delhivery is an E-commerce logistics solution.
17track - All-in-one package tracking
Shiprocket X - Cross-Border Shipping Made Easy