Finage is a stock, currency, cryptocurrency, indices, and ETFs real-time & historical data provider.
Finage API is a free Finance API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Details from finage.co.uk.

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Official-source financials, segments, valuation, peers and prices for KR, US, JP, TW companies
The Finage API is provided by Finage (finage.co.uk).
Yes. The Finage 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.
Yes. The Finage API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Finage API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Finage API is served over HTTPS, so it's safe to use in production.