Vienna, Austria is a hub for cryptocurrency enthusiasts and traders, with a number of popular cryptocurrency exchanges operating in the city. Some of the most well-known exchanges in Vienna include:

1. Bitpanda: Bitpanda is one of the largest and most popular cryptocurrency exchanges in Vienna. It offers a wide range of cryptocurrencies for trading, as well as fiat-to-crypto and crypto-to-crypto trading pairs. Bitpanda is known for its user-friendly interface and strong security measures.

2. Coinfinity: Coinfinity is another popular cryptocurrency exchange in Vienna that offers a variety of cryptocurrencies for trading. It also provides a Bitcoin ATM service for users to buy and sell cryptocurrencies in person. Coinfinity is known for its excellent customer service and transparent fee structure.

3. Bitcoinbon: Bitcoinbon is a unique cryptocurrency exchange in Vienna that allows users to purchase Bitcoin vouchers from various retail locations across the city. Users can redeem these vouchers for Bitcoin on the Bitcoinbon platform. Bitcoinbon is popular among users who prefer to buy Bitcoin in person rather than through online exchanges.

4. Coinfinity OTC: Coinfinity OTC is a branch of Coinfinity that offers over-the-counter trading services for high-volume traders and institutional investors. It provides personalized service and competitive pricing for large cryptocurrency trades. Coinfinity OTC is popular among professional traders looking to execute large transactions securely and efficiently.

Overall, Vienna has a vibrant cryptocurrency community with a number of popular exchanges catering to both casual traders and experienced investors. Whether you are looking to buy Bitcoin in person, trade a variety of cryptocurrencies online, or execute large transactions over-the-counter, Vienna has a cryptocurrency exchange to suit your needs.