
US address standardization, congressional and state legislative districts, Census data; free tier.
RevAddress API is a free Data Validation API that requires apiKey authentication, is served over HTTPS and does not support CORS, so it should be called from a server.
Complete API reference for RevAddress USPS v3 REST API. Authentication, endpoints, rate limits, and error handling.
Details from revaddress.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.
Parse freeform US addresses into structured fields (house number, street, unit, city, state, ZIP)
The RevAddress API is provided by RevAddress (revaddress.com). Complete API reference for RevAddress USPS v3 REST API. Authentication, endpoints, rate limits, and error handling.
Yes. The RevAddress API is listed in the Data Validation 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 RevAddress API uses apiKey authentication, so you need to register for credentials before making requests.
Not directly. The RevAddress API does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The RevAddress API is served over HTTPS, so it's safe to use in production.