Evaluating fraud risk in a transaction between consumer and a merchant over a network is disclosed. The merchant requests service over the network using a secure, open messaging protocol. An e-commerce transaction or electronic purchase order is received from the merchant, the level of risk associated with each order is measured, and a risk score is returned to the merchant. In one embodiment, data validation, highly predictive artificial intelligence pattern matching, network data aggregation and negative file checks are used to examine numerous factors to calculate fraud risk. A risk score is generated and compared to the merchant's specified risk threshold. The result is returned to the merchant for order disposition.