AfterShip - AfterShip is the shipment tracking API for ecommerce businesses and marketplaces.
17track - All-in-one package tracking
OneTracker - OneTracker – Package Tracker is an app by OneTracker Team that helps users track all their delivery vehicles and staff to increase the productivity of their delivery business.
PostTrack.com - Universal Parcel Tracking System
Instant Parcels - Package & Delivery Tracker.
TrackChecker Mobile - TrackChecker Mobile app features tracking of parcels and online orders, so users don’t have to worry about losing a package by tracking the parcel right on their mobile phone screen.