San Francisco-based fintech startup SoFi has launched a cryptocurrency trading service that allows users to trade bitcoin, ether, and litecoin. The company said it will add more cryptocurrencies in the coming months.

The company said users will not be able to withdraw their cryptocurrencies to an external wallet, in order to maintain a closed system that can better secure assets. In the future it may consider adding a transfer feature.

Chief executive officer Anthony Noto, a former chief operating officer at Twitter, said cryptocurrency trading has been the most requested service from its existing customers.

“Feedback from our members has made it clear that a significant percentage are not only interested in learning more about cryptocurrencies but are also already buying and selling crypto,” Noto said in a statement.

The service is being offered by SoFi Digital Assets and is available in 36 states including Alabama, California, and Ohio. It is not available in New York. The minimum order size per transaction is $10, and the maximum order per day, per individual, is $50,000. Customer orders will be filled using Coinbase.

SoFi said the service will be free initially, but it will eventually charge a markup of up to 1.25% on crypto transactions.

“I believe in the power of distributed ledger technology. But one of the things about crypto is it’s not always broadly available in a way that’s easy, transparent, and fast,” Noto said in an interview with Fortune.

SoFi has said its app has over 800,000 users. The company said it is the first platform to offer automated and active investing with stocks, exchange-traded funds, and crypto through a single app.

Fintech companies including Square, RobinHood, and eToro have offered similar services in recent months.