Abstract: A transaction processing system (130) is arranged to receive a transaction request from a user device (110), the transaction processing system (130) comprises a cookie retriever (141) arranged to obtain a cookie (112) stored in a browser application (111) of the user device (110) containing outcome data indicative of an outcome of at least one prior transaction, a processing setter (142) arranged to determine based on the outcome data which of a plurality of transaction processes (152) is to be applied by the transaction processing system (130) to the transaction request, and a transaction processor (143) arranged to process the transaction in accordance with the determined transaction process.