Mita (name changed) is here, there and everywhere, managing her shop alone in Salt Lake, Kolkata as she juggles her spatula, pots, pans, paper plates, teacups, and dish soap. In the midst of this apparent chaos, she does some deft mental arithmetic to calculate dues, and tells her customers, “The QR code is displayed there.” Mita is one among the wide cross section of the Indian population who have adopted United Payments Interface (UPI)—a real-time, cash-less and secure payment system. The National Payment Corporation of India (NPCI) introduced UPI in 2016 to facilitate inter-bank transactions for peer-to-peer, or individual-to-merchant transactions.…