In my opinion, the most important feature in an e-commerce fraud prevention tool is real-time fraud detection, because online transactions happen instantly and suspicious activities must be identified before fraudulent purchases are completed. Real-time detection uses AI, behavioral analysis, and risk scoring to quickly identify unusual patterns such as stolen payment methods, account takeovers, or suspicious buying behavior, helping businesses prevent financial losses and chargebacks. While features like reporting, automation, integration, and user authentication are also important, they are most effective when fraud can be detected and blocked immediately. Therefore, strong real-time fraud detection directly reduces risks, protects customer transactions, and builds trust in the e-commerce experience.