Unified Payments Interface is an instant real-time payment system developed by National Payments Corporation of India (NPCI). The interface facilitates inter-bank peer-to-peer (P2P) and person-to-merchant (P2M) transactions. It is used on mobile devices to instantly transfer funds between two bank accounts. The mobile number on the device is required to be registered with the bank. The UPI ID of the recipient can be used to transfer money. It runs as an open source application programming interface (API) on top of Immediate Payment Service (IMPS),and is regulated by the Reserve Bank of India (RBI).

As of September 2022, there were 358 banks available on the platform with a monthly volume of 6.7 billion transactions amounting to ₹11.16 lakh crore (US$140 billion).

As of May 2021, the platform has over 10 crore (100 million) monthly active users in India. The proportion of UPI transactions in total volume of digital transactions grew from 23% in 2018–19 to 55% in 2020–21 with an average value of ₹1,849 per transaction. Digital transactions worth ₹8.31 lakh crore were made via the platform in January 2022. In FY 2021–22, the value of transactions crossed $1 trillion.

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