Nomics' API is the best free cryptocurrency & bitcoin (market data) API available. It has no rate limits and is lightning fast, free & beloved by developers. The API is a lightning fast RESTful JSON API; it aspired to be crypto's data backbone.
ExchangeRate-API is an easy to use HTTP API for e-commerce & other websites to show pricing data in different currencies. It's been running since 2010 and offers both free and paid plans.
A fast, developer-friendly currency rates API that delivers accurate live and historical FX data for applications of any size. It returns clean JSON over HTTPS, supports CORS, and uses straightforward API-key authentication.
