The USPS ZIP Code Lookup Web Tool API allows developers to get the ZIP Code and ZIP Code + 4 corresponding to a given address, city, and state. This API can process up to five lookups per request.
This API is part of the USPS Web Tools API library which provides access to USPS data free of charge.
Developers who are producing shipping, eCommerce, or location-based services may find that determining ZIP codes or International postal codes is crucial to creating a successful application. In order to accomplish this, developers would need a suitable ZIP Codes API. Here are 10 popular choices.