Working with the USPS Shipping API is not fun. The fact that it requires at least one (1) phone call to USPS Internet Customer Care Center (ICCC) to get activated is a show-stopper in my opinion. If you aren’t in a hurry to get anything done today, you can email for activation instead of calling.
A long time client of mine is using OpenCart, which is a favorite open source shopping cart. He acquired a USPS shipping label module that needed to be installed to make his life easier. Not sure if he had to pay for the module or not, but it needed a little tweaking before it would work properly…
