AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
17track - All-in-one package tracking
OnTime 360 - Cloud-based courier software with online order entry, route optimization, and dynamic tracking. The complete delivery software solution.
PostTrack.com - Universal Parcel Tracking System
couriermanager - Try couriermanager! A software solution designed especially for courier companies management. Organization, efficiency and productivity!
Instant Parcels - Package & Delivery Tracker.