Free Address Verification/Standardization

USPS webtools is expensive, and Google Maps doesn't have certain addresses. Are there any free or open-source solutions?

Depending upon the nature of your business, or if you're a non-profit or educational institution, there is one online provider that gives you free address verification: SmartyStreets. Up to this point, I've never seen another online provider offer their services for free.

UPDATE: SmartyStreets now has a free offering for any company of any kind, up to a certain amount of lookups per month.

In the interest of full disclosure, I'm the founder of SmartyStreets. You're more than welcome to contact me personally with additional questions.