PayPal data scientist Venkatesh Ramanathan presents an early production case study on using H2O's deep learning for fraud detection across PayPal's transaction, account, and network-level risk layers. He walks through the practical struggles of running deep learning at scale on a 10-million-row, 1,500-feature Hadoop dataset, including cluster memory limits, slow data import, and missing values, and how direct collaboration with H2O's engineering team resolved each one. He closes with tuning results across hidden layers, activation functions, and feature subsets, including a measured AUC improvement from deep learning's automatic feature derivation.