This book constitutes the revised selected papers of the 15th International Conference, MEDES 2023, Heraklion, Crete, Greece, May 5–7, 2023 The 29 full papers included in this volume were carefully reviewed and selected from 52 submissions. The papers focus on the following topics: Design Issues & BlockChain, Query Processing and Visualization, Learning Issues, Services and Systems, Business and Communication Technologies, Digital Twin and Security, Architecture Technologies, Time and Text Management.