Towards a multi-level geographical framework of SME open innovation: local-to-global from bibliometric and topic modeling insights and a research agenda

Despite considerable growth, research on open innovation (OI) in small-and medium-sized enterprises (SMEs) remains theoretically fragmented, lacking integrative efforts that connect foundational theories with contemporary developments. This study synthesizes the theoretical foundations and the current landscape of SME OI research while also highlighting future research directions. Through a comprehensive analysis of 463 publications, utilizing bibliometric analysis, topic modeling, and a systematic, thematic review, we identify three foundational clusters, namely, theoretical legitimacy of OI, external knowledge-based innovation, and SME-specific innovation dynamics, as well as fifteen existing research themes. Our primary contribution is a multi-level geographical framework revealing how SME OI operates across five interconnected scales, including local, regional, national, international, and global. This framework illustrates a structural shift from proximity-based collaboration to hybrid digital-physical networks, where digital engagement enhances local relationships rather than replacing them. Consequently, capabilities developed at one level should be scaled and adapted as SMEs expand across contexts, while wider institutional coordination structures operate concurrently. Finally, we outline key future research directions to advance both theoretical and practical insights into open innovation in SMEs.