European digital banking outfit Revolut is now letting its customers buy, hold and exchange cryptocurrency from within its app.

Blockchaiiiiinnnnn. We're rolling out bitcoin to more of our most active customers. Swipe right from your Cash Card to see if you have it. #satoshi pic.twitter.com/iMxHg1vRAg — Cash App (@CashApp) December 6, 2017

The firm's customers will be able to get their hands on Bitcoin, Litecoin and Ethereum in a matter of seconds.Users can then hold their cryptocurrency within the Revolt app or transfer it to other customers for free. If a user has no fiat currency in their account, they can still use their card, with Revolut dynamically converting any Bitcoin at "the best possible rate".In what Revolut claims is a world first, users can also buy their cryptocurrency in all 25 base currencies, eliminating the FX fees people can face when they buy on most exchanges.The new service comes as cryptocurrencies are gaining huge mainstream interest driven by the momentous rise of Bitcoin, which hit the $10,000 mark at the end of last week. Exchanges have been straining under the weight of visitors, with Coinbase's site suffering outages as hundreds of thousands of people signed up to join the crypto-gold rush.Revolut, which last month hit the one million user milestone, says that 10,000 of its customers signed up to test the beta version of its cryptocurrency service in just six days. The company is confident that it will attract many more with the full launch, promising to stick to a 1.5% markup during the exchange process with no hidden fees.Nikolay Storonsky, CEO, Revolut, says: "Despite being one of the hottest trends in the world right now, getting exposure to cryptocurrency has notoriously been time-consuming and expensive. We’re going to open up cryptocurrency exposure to everyone, faster than any other platform on the market."More evidence of cyptocurrencies moving mainstream comes from Square, which is rolling out the ability to buy and sell bitcoin on its person-to-person Cash App.