This book constitutes extended revised selected papers presented during the 8th Workshop of Human-Computer Interaction Aspects to the Social Web, WAIHCWS 2017, held in Joinville, Brazil, in October 2017, and during the 9th Workshop of Human-Computer Interaction Aspects to the Social Web, WAIHCWS 2018, held in Belém, Brazil, in October 2018.  The 5 full papers presented were thoroughly reviewed and selected from 14 submissions for WAIHCWS 2017 and 3 full papers were selected for publication from 20 submissions for WAIHCWS 2018. The authors were given the opportunity to extend and revise the papers after the conference. The topics included in this volume cover the following fields connected to the social web: user experience, emotion analysis, interoperability, systems-of-information systems, knowledge-intensive processes, ontology, transportation domain, mobile systems, privacy policies, digital legacy, social networks, recommendation models, scientific events, accessible web, software ecosystems, and sustainability.