Comparative Study of Different UPI Apps Special Reference to Success Rate of Transaction

India's digital payments ecosystem has undergone a dramatic structural shift since the Unified Payments Interface (UPI) was launched by the National Payments Corporation of India in 2016. While aggregate transaction volumes continue to set new records, the granular experience of individual users - marked by intermittent failures, app-specific reliability gaps, and temporal congestion patterns remains insufficiently studied. This paper presents a structured empirical analysis of survey responses collected from 139 active UPI users to examine five interrelated objectives: (1) the relationship between perceived user-experience quality and transaction success rates, (2) time-of-day and day of week usage and failure patterns, (3) a comparative analysis of transaction attempts versus failures across four major platforms- GPay, PhonePe, PayTM, and native Bank UPI, (4) user-perceived determinants of transaction failure including network issues, server downtime, security protocols, and incorrect user inputs, and (5) a machine-learning-based predictive model to forecast user segments most susceptible to high failure rates. Results indicate that transaction frequency rather than choice of application is the strongest predictor of failure exposure. GPay demonstrates the most favourable attempt to success profile, while Bank UPI's native applications exhibit a near one-to-one ratio of active users to perceived failure votes. The GPay application showcases the best attempt-to-success rate, while Bank UPI's native applications show almost a one-to-one correlation between the number of active users and the perception of a failed transaction. These findings carry practical implications for platform developers, network infrastructure planners, and financial regulators aiming to deepen trust in India's cashless economy.