ONE half of the team that founded Ireland's newest €1bn technology company says that he and his brother are only getting started.
John (23) and Patrick (25) Collison created Stripe, a low-cost way for small companies to accept credit card payments online without administrative and financial hassles.
The service is wildly successful, with thousands of American and European companies now using it.
And it has just received new funding of €60m from some of Silicon Valley's most canny investors. The new funding is said to value the company at around €1.3bn.
But while some entrepreneurs might think of cashing out at this point, the Collisons are only getting started, according to John.
"It's still early days for the payment systems that power the internet," he said. "It's outrageously difficult and expensive to move money between countries.
"Fraud and storing credentials still cause merchants hassle. So online payments is a great place to go hunting for problems worth solving."
The runaway success story began when the Limerick brothers became infuriated by how difficult it was to accept payments from customers online.
"We had found it really hard in our previous business to accept payment over the internet," he told the Irish Independent.
"It felt like many other people would be having the same problem, so we set about solving it."
John and his brother previously created an online auction payments company, which was sold for almost €4m when in secondary school at Limerick's Castletroy College. He also created an iPhone app to review Leaving Cert papers.
John now works from a San Francisco office with brother (former BT Young Scientist winner) Patrick and more than 80 others.
He said that the Stripe service now reaches 12 countries, including Ireland, Britain and the US. He said that the company is processing "billions of dollars" each year.
"We're hoping to get many more countries out the door this year," he said.
Social media giant Twitter is reportedly in discussions with the company over a deal that would allow Twitter to enable companies to accept payments on the social media platform.
Despite the landmark nature of the company's current funding announcement, Mr Collison said that there was no single breakthrough moment for the firm.
"It feels to me more like the product of lots of little breakthrough moments," he said. "It was lots of incremental steps."
He also revealed that the brothers were working on the service long before they announced it to the world in 2011.
"Many people don't know this, but we started working on Stripe almost two years before it launched publicly," he said. "There was a long period where we were writing code to support a small handful of users, and navigating a relatively unfamiliar industry.
"We wrote the first lines of code in October 2009. Three months later, in the following January, we got our first customer. We stayed going, writing code, starting to hire people and trying to find new customers. By the time we launched publicly in September 2011, we were 10 people."
Stripe's biggest rivals include Paypal, the giant online payments system used by eBay.