The Collison brothers made the recent Five Irish under 30 in the Forbes Rich List of ones to watch.
Not surprising so their Stripe online payments firm, seen by many as a threat to giant PayPal, has been valued at $1.75bn in a recent fund raising.
The brothers, Patrick (25) and John (23), are both former pupils of Castletroy College in Limerick and the former was once one a BT Young Scientist award winner.
Now resident in Silicon Valley, they sold their first company Auctomatic to Canadian company Live Current Media for US$5m (€3.2m) when they were 17 and 19.
The company is now live in the US, the UK and Ireland.
Although the majority of companies using Stripe's payment system are small, Mr Collison said Walmart and US-based IT firm Rackspace also use the service.
Stripe recently started its international expansion with trial services in Germany, France, Belgium and Australia. Ireland is the third country, after Britain and Canada, to launch full Stripe services.