USPS Tracking/Delivery Confirmation Label API

USPS Tracking/Delivery Confirmation Label
The U.S. Postal Service provides a suite of USPS Web Tools that customers may integrate into their own websites to validate or find mailing addresses, track and confirm mail delivery, calculate shipping rates, and create domestic or international shipping labels. This service allows users to create a tracking label and an online customer record for a parcel shipped within the US, allowing the user or user's customers to track delivery status of that parcel.