Hello, crypto-exchanges are places, rather, not of exchanging crypto-currencies, but of speculative earnings on courses. There are quite a few of them: Binance, Kraken, Huobi and many others. On exchanges, as a rule, there are quite large turnovers, that is, there are a lot of transactions, so the commissions here are lower than in exchangers. At the same time, the percentage for the exchange of cryptocurrencies that they take will differ from one trading platform to another. Personally, I use the online service Instant currency exchange 24/7 for a quick cryptocurrency exchange.