Senior Software Engineer

Step into the future of connectivity with the Microsoft 365 Substrate First Mile Networking team, where bold innovation meets massive scale. We shape the networking infrastructure that fuels Substrate and COSMIC—critical platforms behind Microsoft’s most impactful productivity experiences like Copilot, Outlook, Teams, and SharePoint. We tackle some of the most complex distributed systems challenges in the industry, driving performance, reliability, and intelligence across global networks. With millions of users depending on our solutions daily, our contributions resonate across the entire Microsoft ecosystem. As a Software Engineer in the Microsoft 365 Substrate First Mile Networking team, you will design and implement scalable networking solutions for the Microsoft 365 Substrate and the COSMIC (container-based) platforms. You will design and optimize first-mile connectivity systems to ensure low-latency, high-reliability access to productivity services. Additionally, you will analyze production service telemetry to identify and implement continuous improvements. This opportunity will allow you to work on foundational infrastructure that powers Microsoft’s most critical services. It will provide an opportunity to solve real-world problems at massive scale with global impact, on a team that values innovation, autonomy, and technical depth.