I am looking for a payment solution for my website using crypto. I have seen some websites that display a modal with a QR code and a recipient address. I wonder how they know if someone has deposited funds into that wallet address in order to credit the payment. Usually, with payment gateways, they can transmit additional parameters (such as orderId) and a callback address to confirm that the ID exists in the database.
I don't want to use a third party. I am using the etherjs or web3js library, but the issue is how can I know which user has made a payment for something? Currently, the only thing I can do is retrieve the payment amount.
The problem is that I cannot confirm which user made the payment if the website does not require updating the wallet address before making the payment.
Other websites only have a QR code and the payment amount. How did they manage to solve this?