Gender imbalance in information technology in general, and Free/Open Source Software specifically, is a well-known problem in the field. Still, little is known yet about the large-scale extent and long-term trends that underpin the phenomenon. We contribute to fill this gap by conducting a longitudinal study of the population of contributors to publicly available software source code. We analyze 1.6 billion commits corresponding to the development history of 120 million projects, contributed by 33 million distinct authors over a period of 50 years. We classify author names by gender and study their evolution over time. We show that, while the amount of commits by female authors remains low overall, there is evidence of a stable long-term increase in their proportion over all contributions, providing hope of a more gender-balanced future for collaborative software development.

Stefano Zacchiroli is Associate Professor of Computer Science at Université de Paris on leave at Inria. His research interests span formal methods, software preservation, and Free/Open Source Software engineering. He is co-founder and current CTO of the Software Heritage project. He is an official member of the Debian Project since 2001, where he was elected to serve as Debian Project Leader for 3 terms in a row over the period 2010-2013. He is a former Board Director of the Open Source Initiative (OSI) and recipient of the 2015 O’Reilly Open Source Award.