As of my last update in January 2022, some of the largest cryptocurrency exchanges in the world were:
Binance - Binance is one of the largest cryptocurrency exchanges by trading volume. It offers a wide range of cryptocurrencies for trading and has a global user base.
Coinbase - Coinbase is a popular cryptocurrency exchange based in the United States. It is known for its user-friendly interface and is often the entry point for many people into the world of cryptocurrencies.
Huobi - Huobi is a cryptocurrency exchange based in Singapore. It offers trading in a wide range of cryptocurrencies and has a significant presence in Asia.
Kraken - Kraken is a US-based cryptocurrency exchange known for its security features and wide range of supported cryptocurrencies.
Bitfinex - Bitfinex is a cryptocurrency exchange based in Hong Kong. It offers advanced trading features and is popular among experienced traders.
OKEx - OKEx is a cryptocurrency exchange based in Malta. It offers trading in a variety of cryptocurrencies and derivatives products.
Bittrex - Bittrex is a US-based cryptocurrency exchange known for its security and compliance with regulations.
Please note that the ranking and status of exchanges may have changed since my last update, so I recommend checking current statistics for the most up-to-date information.