The launch of the Unified Payments Interface in April 2016 marked the beginning of one of the most remarkable success stories in the history of financial technology. What the National Payments Corporation of India introduced as an interoperability experiment has since grown into the undisputed backbone of everyday financial exchange for hundreds of millions of Indian citizens — processing an extraordinary fifteen billion transactions every single month in less than a decade. This meteoric rise is a testament to the power of visionary infrastructure, and it is a development that richly deserves the sustained scholarly attention it is, at long last, beginning to receive.

This paper tries to consolidate what the research community has actually found. We draw on roughly forty-five studies, all appearing in Scopus-indexed journals or equivalent peer-reviewed venues published between 2017 and 2024, and ask what they collectively tell us about UPI's role in pushing India toward a less cash-dependent economy. The threads are genuinely varied: some scholars have focused on the psychological and generational determinants of who adopts UPI and why; others have used natural experiments and panel regressions to trace macroeconomic consequences; still others have mapped UPI's uneven penetration into rural India or raised alarms about the fraud problem that has grown alongside the platform's success. Theoretical frameworks from UTAUT and UTAUT2 to Diffusion of Innovation sit alongside more empirically driven approaches. The field has pluralism, which is both its strength and, occasionally, its weakness.

What the synthesis yields is a picture with genuine complexity. Yes, UPI has accelerated India's cashless transition in ways that are measurable and, in some cases, causally identified. Financial literacy has improved, merchant revenues have grown, credit access has expanded into populations that were previously invisible to lenders. But the gains are not distributed evenly, fraud is accelerating, rural penetration remains patchy, and the research base itself has blind spots — particularly the near-complete absence of longitudinal studies. This paper maps all of that, and closes by pointing toward where future empirical work is most needed