InnerSource Circumplex Model: Mapping Cross-organizational Developer Collaboration Patterns with Insights from Japanese Corporate Experience

This paper presents a comprehensive analysis of InnerSource adoption processes and their evolution within enterprises. First, a comparative analysis of Japanese and global enterprises highlights differences in the state of software sharing, perceptions of its importance, and barriers to implementation. Next, this study demonstrates that InnerSource adoption involves multi-layered, topological evolution beyond conventional staged models of program evolution. The research proposes three theoretical frameworks: InnerSource Topologies, which conceptualizes collaborative structures and categorizes internal collaboration levels; the Multi-layered Incentive Model, which combines monetary and non-monetary rewards at individual and project levels; and the InnerSource Circumplex Model, which helps organizations define InnerSource forms based on their specific needs. By mapping InnerSource evolution as a circumplex rather than simple staged progression, leaders can better adjust their focus during implementation. These frameworks help refine the previously ambiguous concept of InnerSource from the perspectives of sharing scope and community growth. These findings reaffirm that successful InnerSource adoption requires the parallel pursuit of top-down program structuring and bottom-up voluntary collaboration. They also contribute to fostering a sustainable innovation culture and enhancing software-sharing practices within enterprises. Furthermore, the newly proposed frameworks, particularly the Circumplex Model, offer versatile guidelines for organizations of varying cultural backgrounds and scales, enabling them to flexibly redefine and introduce InnerSource. This research is thus expected to advance corporate software sharing and spur innovation in diverse industrial contexts.