𝗦𝘆𝘀𝘁𝗲𝗺 𝗗𝗲𝘀𝗶𝗴𝗻: 𝗛𝗼𝘄 𝗨𝗣𝗜 𝗣𝗮𝘆𝗺𝗲𝗻𝘁𝘀 𝗪𝗼𝗿𝗸

You buy a ₹20 chai from a local vendor.

You scan a QR code using Paytm.

Your account is with HDFC Bank.

The vendor uses SBI.

The money moves between two different banks in three seconds.

Here is how that ₹20 moves.

The QR code holds information. It contains the UPI ID and merchant details. It does not hold money.

When you tap pay, Paytm creates a request. Paytm does not move the money. It acts as an interface.

The process follows this path:

The National Payments Corporation of India (NPCI) manages the UPI network. Think of NPCI as a traffic controller. It knows which banks own the accounts and where to route the request.

NPCI sends the request to your bank. Your bank performs four checks:

If these checks pass, your bank debits the money.

NPCI then sends the request to the vendor's bank. That bank verifies the account and credits the amount. Once both banks confirm, NPCI tells Paytm the transaction is successful.

Millions of people use UPI every minute. Banks do not move physical money for every single chai or snack. They use settlement records.

Throughout the day, banks track what they owe each other.

NPCI tracks these totals. Banks settle these balances in bulk later. This method is faster than moving individual amounts every time.

Key reasons for this speed:

The next time you hear a payment success sound, remember the scale. Multiple banks, servers, and networks work together in real time to finish the job.

Source: https://dev.to/khushindpatel/system-design-how-does-a-upi-payment-reach-the-chai-wala-in-just-seconds-nk6

Optional learning community: https://t.me/GyaanSetuAi