Just over a decade ago, Kristo Käärmann and Taavet Hinrikus were looking to cut the costs of converting cash from pounds into euros. It was an idea that lead to the birth of TransferWise. 

Käärmann earned a Christmas bonus in 2008 in London and decided to transfer it to his savings account in his homeland Estonia, where interest rates were higher. He was surprised to find that the British bank used an exchange rate that was about 5% less advantageous to him than the headline exchange rate he saw in Reuters and Bloomberg. 

The business plan he came up with looks like this: Transferwise matches transfers between parties and earn a small commision while using the inter-bank mid-exchange rate, unlike banks and other exchange agents that use buy-and-sell rates, allowing them to keep the difference.

“We are now moving $5.5 billion on behalf of individuals and businesses across borders, so the biggest part of what we do is we help businesses and banks move money across borders,” TransferWise CEO Käärmann said Wednesday on Bloomberg Television. He added that “this is just the beginning. Now we are also bringing in international banking services in about 20 countries, including all of Europe.”

Impact investors might want to keep an eye on TransferWise and its peers. In an increasingly mobile world with more than 244 million migrant workers there’s no shortage of potential customers for cash transfers. By slashing the cost of remittances, these companies are both making a profit while helping slash poverty.

Unlike many startups that have found a promising niche, TransferWise’s founders aren’t planning to go public anytime soon. They’re happy to let the company grow organically. There’s been no shortage of investors in the eight years since the company’s launch. Richard Branson, PayPal founders Max Levchin and Peter Thiel, former Betfair CEO David Yu, and Wonga.com co-founder Errol Damelin are among the company’s backers.

“We are indeed the unusual unicorn in that we are profitable,” Käärmann said. “We’ve been profitable for the last three years. Therefore, we haven’t needed to raise extra capital for the company, however, we have raised plenty of money.

In May, TransferWise announced a $292 million investment that wasn’t meant to add money to the balance sheet. The aim was to allow employees and early investors an opportunity to sell some of their stake in the company. The deal left the company with a $3.5 billion valuation, making it Europe’s most-valuable fintech startup. The brainchild of Käärmann and Hinrikus has gone from 1 million customers in 2016 to 5 million now.

The deal enabled the company “to provide liquidity to our shareholders, to early employees, and bring on new ones more appropriate for our stage of growth,” Käärmann said. “So we are getting the benefits of public markets and we are doing it privately today. As it stands now, we have no immediate plan to list it on any public exchange.”

“We are indeed the unusual unicorn in that we are profitable.”

They aren’t the only startup that’s taken on the banks and Western Union in providing currency transfer services. CurrencyFair, Midpoint, Kantox and PeerFX have been founded over the past decade with at least some similar offerings.

TransferWise has introduced new services in addition to transferring currencies, such as a borderless account and a multi-currency Mastercard debit card. The corporate headquarters remains in London, while there are regional hubs in Singapore, Brussels and elsewhere.

“Two months ago we launched in Australia and New Zealand,” Käärmann said. “Last month we rolled out our multi-currency debit card in Singapore. Now we are starting to cover Asia with international banking propositions, and see a good take up there.” 

The company announced Thursday that it would be giving away the $110,000 prize it won earlier this week at the Singapore Fintech Festival. TransferWise will be giving away the funds to Singaporean people and businesses that have been hit by hidden bank fees.

One financial area that TransferWise isn’t looking to enter is lending, at least in part because of regulatory requirements, Käärmann said.

“We don’t actually hold banking licenses anywhere in the world because we don’t lend the deposits,” Käärmann said. “We do hold plenty of customers’ deposits. Actually a few months ago we recorded more than one billion pounds worth of deposits, but we don’t lend them out to other people, so we are kind of a non-lending bank, if you like.”

Karma’s Scarlett Kuang contributed to this story