A lot of projects need address verification, so it could be beneficial to develop a reusable address verification adapter for services that do address verification.

• USPS could be a nice default. https://developer.usps.com/addressesv3
• We've used smarty streets on a project before as well https://www.smarty.com/products/us-address-verification
• Google powers google maps so might have good API too https://developers.google.com/maps/documentation/address-validation/overview
• and there are services from fedex and ups as well