US zip code distance, radius and location API.
ZipCodeAPI is a free Geocoding API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
US and Canadian Zip Code Distance, Radius and Location API.
Details from zipcodeapi.com.

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Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Get information about place such as country, city, state, etc
Get the country, state, and city of any US zip-code
The ZipCodeAPI is provided by ZipCodeAPI (zipcodeapi.com). US and Canadian Zip Code Distance, Radius and Location API.
Yes. The ZipCodeAPI 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 ZipCodeAPI uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the ZipCodeAPI is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The ZipCodeAPI is served over HTTPS, so it's safe to use in production.