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.