Coinmarketcap, some alternatives:
CryptoCompare https://www.cryptocompare.com/
CoinGecko https://www.coingecko.com/en
Live Coin Watch https://www.livecoinwatch.com/
CoinCodex https://coincodex.com/
OnChainFX https://messari.io/onchainfx
https://thebitcoinnews.com/best-coinmarketcap-alternatives-2019-guide/