
Validate and append data for any US ZipCode.
US ZipCode API is a free Geocoding API that requires apiKey authentication, is served over HTTPS and supports CORS, so it can be called from the browser.
Instructions on how to easily look up, verify and append ZIP Code data using the US ZIP Code API from Smarty.
Details from smarty.com.

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The US ZipCode API is provided by Smarty (smarty.com). Instructions on how to easily look up, verify and append ZIP Code data using the US ZIP Code API from Smarty.
Yes. The US ZipCode API is listed in the Geocoding category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The US ZipCode API uses apiKey authentication, so you need to register for credentials before making requests.
Yes. The US ZipCode API supports CORS, so front-end JavaScript can call it directly.
Yes. The US ZipCode API is served over HTTPS, so it's safe to use in production.