Principal Software Engineer (Substrate Store)

We are the Store team within Microsoft’s Substrate Storage Fabric — the core platform that powers Microsoft 365 experiences, from AI-powered Copilot innovations to Outlook and Teams. Our team focuses on API optimization, search running on Azure, and the security posture of the storage access path. We are looking for a Principal Software Engineer (Substrate Store) to lead the modernization of Store Access. If you’re passionate about building latency-critical access APIs and high-throughput services that run on both BareMetal and Azure at a global scale, this role gives you the opportunity to shape one of Microsoft’s most strategic products. You will lead complex architecture and implementation across teams, make high-judgment technical decisions that affect service reliability and customer trust, mentor engineers, and drive measurable engineering excellence. Operating at Principal scope, you will break hard cross-team problems, create clarity for multi-year technical outcomes, and set the conditions for your team and partner teams to deliver safely at global scale.   Microsoft’s mission is to empower every person and every organization on the planet to achieve more. As employees, we come together with a growth mindset, innovate to empower others, and collaborate to realize our shared goals. Each day we build on our values of respect, integrity, and accountability to create a culture of inclusion where everyone can thrive at work and beyond.

Lead architecture, design, and implementation for Store Access modernization — latency-critical access APIs, search on Azure, and integration with the broader Substrate storage fabric and M365 dependencies. Drive API optimization at scale — define high-throughput, low-latency access contracts, concurrency and resource-governance models, caching, and back-pressure, balancing latency, cost, and reliability. Own the search-on-Azure technical direction — lead the design and scaling of search/indexing systems on Azure infrastructure, including index freshness, query performance, and cost efficiency. Own and broker cross-team architecture decisions across upstream and downstream dependencies, ensuring designs meet performance, scalability, resiliency, disaster-recovery, cost, security, privacy, compliance, and accessibility expectations. Lead by example in engineering craft — produce extensible, maintainable, well-tested, secure, performant code in C# and Rust, and review code and test code for diagnosability, reliability, maintainability, security risks, compliance, and appropriate coverage. Define the optics — quality metrics, telemetry, dashboards, and feedback loops that guide technical decisions, measure customer value, surface risks early (especially latency and security regressions), and improve service health. Apply AI-native development practices responsibly, including appropriate controls over AI-generated requirements, designs, code, tests, and operational assets; evaluate AI tools and practices that improve engineering productivity and quality.

Required Qualifications: Bachelor's Degree in Computer Science or related technical field AND 6+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python OR equivalent experience.

Master's Degree in Computer Science or related technical field AND 8+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python OR Bachelor's Degree in Computer Science or related technical field AND 12+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python  OR equivalent experience. 2+ years acting as a Principal Engineer (or equivalent), with clear ownership of architecture, design decisions, and technical direction across multiple