These two volumes constitute the proceedings of the 21st International Conference, ICSOC 2023, held Rome, Italy, during November 28-December 1, 2023. The 35 full papers and the 10 short papers included in this volume were carefully reviewed and selected from 208 submissions. The volumes focus on cutting-edge topics like artificial intelligence, machine learning, big data analytics, the Internet of Things (IoT), and emerging technologies such as quantum computing, blockchain, chatbots, and sustainable green IT solutions.