Validating mailing addresses or determining Zip+4 zipcodes

I have a client that is getting hammered by UPS with charges for "address corrections" when customers enter a shipping address that is (even slightly) incorrect. Does anyone know of a database or a web service (paid or free) that can: #1. Verify a complete mailing address? #2. or provide a Zip+4 zipcode when a complete mailing address is passed to it? Either will go a long way to recifying my clients current situation with UPS. Do any CFers have any experience implementing something like this? Thanks, Che

Perhaps: http://www.usps.com/webtools/address.htm ----- Excess quoted text cut - see Original Post for more -----

If they're using UPS already, UPS has address validations tools (city, state, zip) and (street level) https://www.ups.com/upsdeveloperkit?loc=en_US - Gabriel ----- Excess quoted text cut - see Original Post for more -----

John/Dorioo thanks for the links! Free APIs are my friend. :) If they're using UPS already, UPS has address validations tools (city, state, zip) and (street level) https://www.ups.com/upsdeveloperkit?loc=en_US - Gabriel