A Comprehensive Review of the Unified Payments Interface (UPI) in India

Since its introduction in 2016, the Unified Payments Interface (UPI) has become the backbone of India’s shift from cash-based to digital payments. Research on UPI has grown quickly, but it is scattered across adoption, security, performance and policy questions. This review traces how that research has developed and identifies what remains unresolved. Structured searches of Google Scholar and other databases, using UPI-specific key phrases, identified English-language journal articles, conference papers, technical reports and reviews published between 2016 and early 2026. The 53 sources retained were read in full, assigned to eight thematic pillars and interpreted in chronological order. SWOC and ABCD analyses consolidate the evidence. UPI scholarship has moved through three phases: descriptive work on architecture and benefits (2017–2019); theory-driven studies of adoption, satisfaction, security and pandemic-era scalability (2020–2022); and, from 2023, machine-learning fraud detection, segment-specific adoption research and analyses of global expansion. Convenience, trust, perceived risk and digital literacy recur as determinants of use, whereas technical failures, fraud and uneven infrastructure persist as constraints. Technological development has outpaced empirical evidence, and most studies examine a single aspect of UPI. The review extends earlier systematic work on digital payments and UPI by placing eight thematic pillars on one timeline and converting them into a research agenda. The findings are relevant to policymakers, payment service providers and scholars working to consolidate UPI’s role in building a less-cash society.