Abstract: A transaction processing system provides improved flexibility and capability by customizing content provided to the purchaser as the transaction takes place. Content is determined by evaluating one or more rule sets using information previously obtained about the customer and/or the details of the transaction itself. A rules manager module receives a notification from a web server when customer performs a triggering event such as requesting a particular web page from the server. The rules manager provides notification of the event to a rules engine module that suitably retrieves an event tree associated with the event. The event tree contains one or more sets of rules that are evaluated by the rules engine using customer and/or transaction data to produce a catalog of customized actions. The actions are then returned to the rules manager module for creating customized content for the customer.