This book constitutes the refereed thoroughly refereed post-workshop proceedings of the 18th International Conference on Web Engineering, ICWE 2018, held in Caceres, Spain, in June 2018. The 18 revised full papers were selected from 40 submissions. The workshops complement the main conference and explore new trends on core topics of Web engineering and provide an open discussion space combining solid theory work with practical on-the-field experience. The workshop committee accepted five workshops for publication in this volume: First International Workshop on Maturity of Web Engineering Practices (MATWEP 2018), Second International Workshop on Engineering theWeb of Things (EnWoT 2018), Fourth International Workshop on Knowledge Discovery on the Web (KDWEB 2018), International Workshop on Engineering Open Data (WEOD 2018), First International Workshop on Knowledge Graphs on Travel and Tourism (TourismKG 2018).