1. CoinMarketCap: An extensive API for accessing cryptocurrency data.
2. CoinGecko: An open source cryptocurrency data platform with APIs available for developers.
3. CryptoCompare: A comprehensive API for accessing cryptocurrency market data and exchanges.
4. BlockCypher: A secure, reliable and powerful blockchain infrastructure API for developers.
5. Kraken: A cryptocurrency exchange API with a wide range of features and functionality.
6. Blockchain Exchange Rates API: A simple, straightforward API for getting the latest exchange rates of cryptocurrencies.
7. Messari Cryptodata API: A free toolkit for accessing real-time and historical crypto asset data from dozens of exchanges, including prices, order books, trades, candlesticks, OHLCV, and more.
8. Nomics Exchange Rates & Currency Conversion API: An easy-to-use currency conversion and exchange rate API built on top of the Bitcoin blockchain network that supports all currencies and cryptocurrencies in circulation today.

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