
Elixir and Erlang package versions and docs.
Hex API is a free Development API that requires no API key, is served over HTTPS and has unconfirmed CORS support.
Specifications for using and implementing Hex protocols
Details from github.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.
Basic DNS query via HTTP GET request
The Hex API is provided by hexpm (github.com). Specifications for using and implementing Hex protocols
Yes. The Hex API is listed in the Development 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.
No. The Hex API requires no authentication, so you can start making requests without signing up.
CORS support for the Hex API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Hex API is served over HTTPS, so it's safe to use in production.