Seychelles based cryptocurrency exchange.
Huobi API is a free Cryptocurrency API that requires apiKey authentication, is served over HTTPS and has unconfirmed CORS support.
Details from huobiapi.github.io.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
Exchange rates between 162 currency & 300 crypto currency update each 5 min, accurate, no limits
The Huobi API is provided by Huobi API Reference v1.0 (huobiapi.github.io).
Yes. The Huobi API is listed in the Cryptocurrency 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 Huobi API uses apiKey authentication, so you need to register for credentials before making requests.
CORS support for the Huobi API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Huobi API is served over HTTPS, so it's safe to use in production.