How to create an own UPI payment gateway?

To accept UPI payments for an online business, integrate with an established payment gateway. For example, to enable UPI on Paytm Payment Gateway, you must create a merchant account and generate API keys on the Paytm Merchant Dashboard. After choosing a UPI flow (Intent or Collect), integrate the official SDKs/APIs with your website or app, test transactions, and then go live to accept payments.