Jelte spent most of his working life building truly innovative and solid financial technology. From operating systems for smart card chips, to card and terminal technology for the major card schemes, to backend systems for card issuers, and stored value tachnology - as CTO of a number of specialist companies Jelte has built it. Jelte was one of the first team members of the company that first attempted to commercialise electronic cash - David Chaum's DigiCash in the 1990's.