This Pathways to Enable Open-Source Ecosystems (POSE) project helps a wide range of computer users develop and test the next generation of distributed applications in realistic settings. As the world becomes increasingly connected and digital technologies expand across various industries, commerce, research, education, and everyday life, it becomes ever more challenging to design computer systems that perform well under real-world conditions. This project, the Network Simulation Bridge (NSB), provides developers, practitioners, students, and researchers with a means to seamlessly connect distributed applications and services running on actual devices or in simulated environments to network simulation platforms. This collaboration will enable better understanding and insight into how these applications are impacted by the communications networks they depend on. To keep pace with evolving technology, the project will expand NSB’s current user base and establish an open-source ecosystem (OSE) that supports long-term use and ongoing improvement. By supporting a wide range of users and application domains, NSB can help shape more reliable and adaptable technologies in ways that benefit society broadly. This POSE project develops an open-source ecosystem (OSE) around the Network Simulation Bridge (NSB) - a co-simulation framework that enables application developers, researchers, academics, and students to connect their distributed applications to network simulation backends. The