UPI (Unified Payments Interface) is a real-time payment system in India developed by the National Payments Corporation of India (NPCI) and regulated by the Reserve Bank of India (RBI). It enables direct bank-to-bank transfers instantly using a smartphone, without the need for intermediary wallets. Although UPI was not originally designed for wallet integration, several major wallets in India, such as Amazon Pay, PhonePe, Fampay, and OneCard, have incorporated UPI functionality, enhancing its usability and convenience.