This book constitutes revised selected papers from the 12th and 13th International Conference on Cloud Computing and Services Science , CLOSER 2022 and CLOSER 2023, which took place as a virtual event in April 2022 and in Prague, Czech Republic, in April 2023.  CLOSER 2022 received a total of 45 submissions out of which 3 papers are included in this book. From 46 submissions received for CLOSER 2023, 7 papers have been selected for inclusion in this book. They focus on latest advances and various aspects of cloud computing and the link to services science.