Public access to a database of IIN/BIN information.
Binlist API is a free Finance API that requires no API key, is served over HTTPS and has unconfirmed CORS support.
Details from binlist.net.

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The Binlist API is provided by binlist.net (binlist.net).
Yes. The Binlist API is listed in the Finance 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 Binlist API requires no authentication, so you can start making requests without signing up.
CORS support for the Binlist API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Binlist API is served over HTTPS, so it's safe to use in production.