usps credentials

i am developing shopping cart site in which i want to use USPS(united states postal service)for shipping.can anybody know the fields which are to be required for th开发者_运维技巧is service.

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Full details on the USPS API can be found here:

• USPS Web Tools

The fields that are required depend on which service you are using. The parcel tracking service, for example, requires only a username and tracking ID.