Ask HN:Payment Platforms for Validating Users

Hi,

I am starting a new project, and I want all users to be valid users and preferably unique.

I was thinking of using Paypal, and depositing a cent or so into their accounts to validate them, and then as such I know they are most likely unique and valid users.

Does anyone else have any suggestions of different payment platforms to do the same? or another way to validate a user and have a mechanism to pay them at the same time?