Coingecko - CoinGecko is a free to use web-based and mobile application that provides financial market data for more than 2000 digital currencies.
CoinMarketCal - All crypto events that help crypto traders at one place
CoinCap.io - Shows the prices of different cryptocurrencies from ShapeShift.
Coinwink - Crypto alerts, watchlist and portfolio tracking app for Bitcoin, Ethereum, and other 3500+ crypto coins and tokens
CoinStats - CoinStats is a cryptocurrency research and portfolio tracker, that allows to access market data on over 3000 cryptocurrencies, track bitcoin and altcoin investments.
Cryptorch API - Cryptorch API is an AI-powered machine learning utility that is used in forecasting the prices for various cryptocurrencies from Bitcoin to BitTorrent.