Who needs a tracking service when you can just hop on the USPS, FedEx, UPS, or DHL website (or whoever your carrier is) and just track? Maybe you. The Trackthis API integrates an amazing array of functions into your application. The API webpage lists over 10 carriers you can get notifications for. As Trackthis explains, you can get notice via Twitter, Facebook, email, etc., and get the notification that's meaningful to you.
Trackthis gives the user control. You get push notifications, can track multiple packages from different carriers, and you can choose what you want to be notified about: every time a package changes status, to only when it is out for delivery, as well as options in between. And they have it on the iPhone as well. In short, you just don't have to mess with carrier websites or be locked in to how and when carriers want to notify you.
The service is a leap forward in convenience, as Kath Weaver posted in an iTunes review,
I really LOVE your tracking service. It works very well! Better than the real tracking services.
More features are on the way.
Why use Trackthis? It's elementary!