TopOPPS Developer Wins MasterCard’s Hackathon By Suzanne Iovaldi on November 20, 2014 (updated December 1, 2015) TopOPPS developer, Darius Calliet, was part of the winning team at MasterCard’s Give-Back-a-Thon over the weekend of November 15, 2014. Read more about his team, Pennies for Change.