Developer Contributions and Self-Admitted Technical Debt: A Longitudinal Case Study In Industry

The accumulation of technical debt affects maintenance effort, system quality, and the way teams evolve their code bases over time. In this paper, we investigate how developer contribution patterns and self-admitted technical debt (SATD) co-evolve in a long-lived industrial software system. We analyze nine years of history (2017–2025) from the main Git repository. Using a mining software repository approach, we extract yearly counts of commits, added, removed, and edited lines of code. We further enrich the dataset with manually assigned seniority information for each active developer and year. The resulting dataset is organized by year, developer, contribution level, and SATD type to answer three research questions: (i) how contribution patterns evolve as the project grows; (ii) how SATD is distributed among developers with different contribution and seniority levels; and (iii) how the type and frequency of SATD change as the project matures. Our results show that contribution volume does not scale linearly with team size, and that a small subset of high-impact developers accounts for most SATD across years. We also observe that overall SATD, and in particular defect-related SATD, decreases as the team becomes more experienced. These findings provide empirical evidence on the interplay among contribution behavior, seniority, and SATD in a real-world project and highlight the need to monitor both process changes and individual developer profiles when managing technical debt.