From $19.95 US for a single-user license
Developed by DataIsland Software, USPS Verify is a BlackBox™ program you integrate into your solution to take care of the coding and communication between your desktop or server and the United States Postal Service servers.
Pass an address or part of an address to USPS_Verify and it will query the U.S.P.S. servers and return a full, correctly formatted address.
USPS_Verify works both on a local desktop or installed on FileMaker Server 7 or 8. It includes functions to auto update or install the Troi URL plugin on any desktop as part of its operation. You can use an unregistered version of USPS_Verify with the demo verification server but it must be licensed in order to use it in a live solution.