US Patent 11995624 System-based detection of card sharing and fraud

This disclosure describes, in part, a payment service that associates customer profiles with an identifier of a payment instrument, and then uses the customer profiles to identify a customer that is using the payment instrument during a transaction with a merchant. For instance, in some examples, the payment service can identify preferences of customers using transaction information that includes an identifier for a payment instrument, and associate the preferences with respective customer profiles. The payment service can then receive transaction information associated with a transaction between a customer and a merchant, identify preferences of the customer using the transaction information, compare the preferences of the customer with preferences stored in the customer profiles, and identify the customer based on the comparing. The payment service can further generate a receipt for the transaction and send the receipt to contact information of the customer.