From a shipping confirmation email you received from an online retailer. At the bottom of the peel-off portion of your USPS Tracking label. Your USPS tracking number looks like 9400 1000 0000 0000 ...

Shippo is a shipping API that connects you with multiple shipping carriers (such as USPS, UPS, DHL, Canada Post, Australia Post, UberRUSH and many others) through one interface. Print a shipping label ...

This is the preferred method for shipping packages. With Sendpro you can: Process and print shipping labels for UPS, Fedex, and USPS Compare rates and service options between all three carriers Create ...