Fintech start-up Revolut launched its app in Australia on Thursday, marking its first expansion outside of Europe.The online banking platform said it would gradually sign up 20,000 Australians already on a waiting list, while new customers will have to wait a little longer.Revolut has grown rapidly since it was founded in 2015, racking up more than five million customers in total. By contrast, German rival N26 said earlier this year it has over 2 million users.The digital bank gained popularity for its foreign exchange service which offers the real exchange rate, and has added more features to its platform in recent years, including business accounts and cryptocurrency trading.Will Mahon-Heap, Revolut’s expansion manager for the Asia-Pacific region, said the company won’t offer those extra features in Australia yet as it’s taking a « measured approach. » « Sending money between the U.K., Europe and Australia has traditionally been costly and time-consuming, with transfers taking up to three business days to arrive, » Mahon-Heap said in a statement Thursday. « Making them instant and free between Revolut customers is a huge step towards us tearing down financial borders, and will keep money in the pockets of our customers. »Revolut has selected Melbourne for its Australian headquarters and said it will also build smaller teams in Sydney and Perth. It plans to hire up to 30 people in the country by the end of the year.Based in London, Revolut has so far raised $336 million from investors including early Facebook backer DST Global. It was last valued by investors at $1.7 billion.The company is one of a breed of new app-based banking challengers that are trying to compete with established players. It secured a European banking license late last year, joining U.K. peers like Monzo and Starling which have applied for similar permits. It has also obtained licenses to operate in Japan and Singapore.Revolut already has an e-money license in Europe, which is permitted under Australia’s regulatory regime, a spokesman told CNBC. To help enter the Australian market, Revolut says it partnered with a domestic bank, but declined to comment on the name of the lender, which will hold user funds.While apps like Revolut’s have flourished in the age of the smartphone, questions have arisen over whether their breakneck growth could come at the cost of issues like culture and compliance.Revolut received some negative press at the start of the year, with one report highlighting toxic workplace behavior and high employee turnover, while another suggested a system lapse could have led to illegal transactions going through.The company’s CEO Nik Storonsky admitted failings over work culture, but pushed back against reporting over the compliance issue, saying it did not fail to meet regulatory requirements.Meanwhile, competitor N26, which is worth $2.7 billion, came under scrutiny from the German financial watchdog last month, after reports that a customer’s account had been hacked.WATCH: What is fintech?