Principal Software Engineer

This role offers an exciting opportunity to contribute to the innovation and evolution of a system operating at an exceptional scale and speed. You’ll face a wide variety of technical challenges: from designing new features and optimizing performance down to the millisecond, to building scalable infrastructure for containerized services. You’ll work alongside a passionate, world-class engineering team, own major feature areas, and collaborate globally. If you thrive on solving complex technical problems in a dynamic environment, this is the opportunity for you.

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.

Responsibilities

• Design and develop large-scale, distributed online serving systems—including CPU and GPU ranking and inferencing platforms—to support real-time processing of millions of Ad requests per second with high efficiency, extensibility, diagnosability, reliability, and maintainability.
• Lead architecture discussions, create technical design documents, and drive end-to-end solution planning—identifying system dependencies, performance optimizations, and security/compliance requirements across interconnected services.
• Implement features and enhancements with a focus on code quality, maintainability, and scalability; conduct thorough code reviews to uphold Microsoft engineering standards and ensure solutions are production-ready.
• Serve as a Designated Responsible Individual (DRI) for live-site operations on a rotational on-call basis, proactively identifying, resolving, and escalating service degradations or interruptions to maintain high availability.
• Guide testing strategies and quality assurance plans, including unit tests, automation, and telemetry-based diagnostics to validate assumptions, ensure reliability, and drive continuous improvement in service performance.
• Mentor engineers on software engineering best practices, reusable patterns, and tooling; lead efforts to improve performance through debugging, refactoring, experimentation, and instrumentation at scale.
• Drive engineering excellence through compliance with global and local regulations, investment in modern tools and trends, and close collaboration with partner teams to deliver secure, performant, and customer-aligned ad-serving solutions.

Qualifications

Required Qualifications:

• Bachelor'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#, Python
  • OR equivalent experience.
• 8+ years experience in programming with native C++, including writing production-quality code.
  
• 8+ years experience in designing, implementing, and scaling large-scale, distributed online systems with a deep understanding of system architecture and proven ability to profile, analyze, and optimize performance and capacity of native C++ systems in complex, high-throughput environments.

Preferred Qualifications:

• 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 Master's Degree in Computer Science or related technical field AND 10+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#, Java, JavaScript, or Python
  • OR equivalent experience.
• Proven experience in designing, implementing, and validating deep learning systems for real-time online inference.
  
• Solid expertise in optimizing machine le