Financial technology company Revolut now has one million customers in Ireland, in a development which represents a massive threat to the traditional banks.
Younger people are downloading its mobile app in their droves and ignoring banks and credit unions.
Revolut said its customer numbers have doubled in Ireland over the last six months alone, in what finance experts said was extraordinary growth.
Its total number of customers means it has almost one in five of the total number of personal current accounts in the State.
The rapid take-up of Revolut in this country comes at a time when Irish banks are struggling with ageing IT systems that regularly experience outages.
The fintech firm has also launched Revolut Junior in Ireland, which is designed for parents who want their children to gain financial skills and to learn how to use and manage money.
The product is for those between the ages of seven and 17.
Accounts can only be created by a parent or legal guardian who is an existing Revolut user.
Using their own, existing Revolut account, parents will be able to manage their kids' allowances as well as their own in one secure place.
The extraordinary growth of Revolut in this country has been put down to its easy-to-use app.
Initially its main selling point was its lack of foreign exchange fees.
However, customers are now responding to the fact that day-to-day banking transactions can largely be carried out with no fee, as there are no charges for contactless transactions, direct debits or chip and pin transactions.
Daragh Cassidy, of price comparison site Bonkers.ie, said Revolut has helped revolutionise banking since its launch in 2015.
"It has an excellent, easy-to-use, beautiful app which lets you carry out all of your day-to-day banking needs at your fingertips," he said.
Push notifications, security controls and detailed analytics on spending also help give the app a huge edge over anything the main Irish banks currently offer, Mr Cassidy said.
He said its main competitor, N26, has the benefit of a full banking licence in Germany which it has passported to here.
"The only fault is that some businesses and utility companies still won't accept a Revolut Iban, meaning you could have trouble fully switching over your account," Mr Cassidy said.
Revolut has been called Europe's most-hyped fintech.
The London-based company is said to have gained cult brand status among its users.
Its $5.5bn (€5.07bn) valuation has cemented Revolut's status as one of the most promising companies in fintech. This is more than twice the market valuation of Bank of Ireland.
However, Revolut has faced controversy over its founder Nik Storonsky's alleged connections to the Kremlin.
The company gets its banking licence from Lithuania, where politicians called for an investigation into the company last spring, citing national security concerns.
Mr Stornsky denies any Kremlin links, and has written an open letter warning that "fear-mongering is not something that should be taken lightly".