Kraken is the largest crypto-exchange in Europe and the 2nd largest in the US, trading across 56 cryptocurrencies and 7 fiat currencies. Kraken is the largest crypto-exchange in Europe and the 2nd largest in the US, trading across 56 cryptocurrencies and 7 fiat currencies. As one of the largest and oldest Bitcoin exchanges in the world, Kraken is consistently named one of the best places to buy and sell crypto online, thanks to their excellent service, low fees, versatile funding options and rigorous security standards -- but this is only part of the story. They’ve been on the forefront of the blockchain revolution since 2011.