All Currency Exchanges integrate under a single api.
CoinAPI is a free Cryptocurrency API that requires apiKey authentication, is served over HTTPS and does not support CORS, so it should be called from a server.
Documentation hub linking to guides and API references for the Market Data API, Indexes API, EMS API, Flat Files, and Exchange Rates API.
Details from docs.coinapi.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.
Bitcoin blockchain data, fees, mempool, SEC insider trades, Reddit sentiment. x402 micropayments for paid endpoints.
The CoinAPI is provided by CoinAPI (docs.coinapi.io). Documentation hub linking to guides and API references for the Market Data API, Indexes API, EMS API, Flat Files, and Exchange Rates API.
Yes. The CoinAPI 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 CoinAPI uses apiKey authentication, so you need to register for credentials before making requests.
Not directly. The CoinAPI does not allow CORS, so call it from a server, serverless function or proxy instead of front-end JavaScript.
Yes. The CoinAPI is served over HTTPS, so it's safe to use in production.