There are a lot of trading platforms for crypto currency, but it is best to use only the largest and time-tested ones, since they are the most secure, and security is a very topical issue for the still young crypto currency market. Based on this, I recommend the Kraken exchange: it has a higher volume of daily trades, has a high degree of security, 59 currency pairs, and also 2 ways of replenishing the balance: this is a purse and a transfer.