The UPI payment system in India seems to work really well. I'm not sure about the architecture exactly, but there seems to be a way to generate one-time passwords that you can use to pay people a fixed amount. E.g. you go to a website or store, and they display a QR code for payment, which contains the payment recipient information and amount of the charge. When you scan it, you are taken to your bank app where you authorize the recipeint and the amount, then you are given a special code in the form of a QR code or alphanumeric code. The person recieving the payment can scan the code to recieve payment ... or if you are online you can paste the alphanumeric code. No other information is exchanged. There's nothing that can compromise your ID or account info.

Pretty amazing!

Insane that a developing country has something so seemless, and meanwhile in the USA my credit card number is stolen online every 3 to 5 years, necessitating cancellations and in some cases (as with Chase) I had to close the entire account as they could not stop the fraud even after issuing 5 new cards over the space of 6 months--somehow the new card authorizations were being ported automatically into some subscription systems.

India had to get rid of cash and move virtually all transactions online to deal with the massive fake currency problem:

https://www.youtube.com/watch?v=XH4TTuW_JcA