Which app is best for UPI without ATM card?

The best app for UPI without an ATM card is one that supports Aadhaar-based UPI registration, a feature introduced by the National Payments Corporation of India (NPCI). This method allows users to set a UPI PIN using their Aadhaar number and OTP verification from UIDAI and their bank, eliminating the need for a debit card. Paytm is one app that supports this Aadhaar verification method for setting up UPI.