What goes on behind the screen when you pay through UPI? | Explained
This article provides a step-by-step technical breakdown of how the Unified Payments Interface (UPI) processes digital transactions between different banks in India. It explains the roles of UPI IDs, the National Payments Corporation of India (NPCI), and the underlying infrastructure that ensures secure and instantaneous fund transfers.
Why it matters
As UPI accounts for nearly half of all real-time payments globally, understanding its backend mechanics is essential for grasping the scale and reliability of modern digital financial ecosystems.
The Unified Payments Interface (UPI) is India’s preeminent digital payments system. In July 2026 alone, it processed 2,366 crore transactions — or around 7,600 transactions per second — in total worth nearly ₹30 lakh crore. Across the 2025-26 financial year, UPI handled 24,160 crore transactions worth ₹314 lakh crore, accounting for 85% of the country’s digital payment transactions by volume. According to the International Monetary Fund, UPI also accounted for a stunning 49% of all real-time payments worldwide in 2025.
Say Selvi has an account in Violin Bank and Shankar has an account in Flute Bank. Selvi wants to send Shankar ₹100 via UPI. First, Selvi tells her UPI app — which could be Google Pay, PhonePe, etc. — whom she wants to pay. Obviously the app will not understand who ‘Shankar’ is. Instead, she will have to tell the app in a language the app understands.
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