Metzger joins from the Microsoft and Accenture joint venture IT consultancy Avanade.

Metzger's most recent assignment was to successfully oversee the back-end integration of Skype with Microsoft Outlook.com and to embed Skype calling capability direct from Outlook.com. Metzger's responsibilities included architecture design, development, operational integration and ongoing management.

Prior to the Outlook.com Skype project he was key member of a small team that was responsible for migrating one of the world's most visited consumer web sites, Harry Potter, to Windows Azure.

"My experience is centred on scaling platforms to reliably manage high volumes of interactions and engagement," Metzger said. "At Ensygnia, we are building the Onescan platform and payment process to meet the highest standards of banking security, while at the same time completing millions of transactions at record speed.

"We're effectively building the world's largest mobile fast lane transaction service - with bank-grade security at its heart," he added. "We want both the banks and the consumers to look at Onescan and know they will get simple, fast, secure mobile transactions - every time and all the time."

Welcoming John's appointment, Ensygnia co-founder and CTO Matt Deacon said: "John brings a wealth of knowledge around scaling platforms to cope with the very highest levels of consumer and business demand. He will work closely with our expanding engineering team to ensure the Onescan mobile payment platform is robust, secure and ready - from the first day - to manage the operational and regulatory compliance requirements of global market."