OverviewAs Microsoft continues to redefine the future of AI, we are seeking passionate engineers to tackle some of the most complex and impactful challenges of our time. Our vision is bold — to build intelligent systems that deeply understand users and adapt across agents, applications, services, and infrastructure.This role focuses on building distributed data systems and APIs that power adaptive, context-aware experiences across Microsoft AI. We aim to make Copilot feel like your Copilot — responsive to your preferences, workflows, and goals — while preserving privacy, security, performance, and scale.We are looking for a Principal Software Engineer to lead the design and development of distributed data infrastructure, APIs and personalization pipelines that drive Copilot’s intelligence. You will work across Microsoft AI and Copilot teams.You will possess a methodical approach to problem-solving, proficiency in backend technologies, a familiarity with applied AI and its unique challenges, and the ability to architect solutions that stand the test of time. The right candidate is hands-on and enjoys building world-class consumer experiences and products in a fast-paced environment. A key skill is the judgment to make the right risk vs velocity and value decisions.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. Starting January 26, 2026, Microsoft AI (MAI) employees who live within a 50- mile commute of a designated Microsoft office in the U.S. or 25-mile commute of a non-U.S., country-specific location are expected to work from the office at least four days per week. This expectation is subject to local law and may vary by jurisdiction.ResponsibilitiesArchitect scalable, low-latency systems for ingesting, processing, and serving personalized signals.Design data models and APIs that enable Copilot to reason about user context, preferences, and historyBuild real-time and batch personalization engines that adapt Copilot’s behavior.Collaborate with privacy, security, and responsible AI teams to ensure personalization is safe, transparent, and user-controlledOptimize for performance, reliability, and cost across diverse workloads and geographies.Ship high-quality, well-tested, secure, and maintainable code.Find a path to get things done despite roadblocks to get your work into the hands of users quickly and iteratively.Enjoy working in a fast-paced, design-driven, product development cycle.Embody our Culture and Values. QualificationsRequired 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++, C#, Java, JavaScript, or PythonOR equivalent experience.Preferred Qualifications:4+ years' experience building scalable services, including securing applications and infrastructure on top of cloud infrastructure like Azure, AWS, or GCP.3+ years' experience in OSS data technology, such as Kafka, Spark, Flink.Experience with large scale data systemsExperience working with AI platforms, frameworks, and APIs. Experience using Machine Learning frameworks, including experience using, deploying, and scaling language learning models, either personally or professionally. Ability to identify, analyze, and resolve complex technical issues, ensuring optimal performance, scalability, and user experience. Demonstrated interpersonal skills and ability to work closely with cross-functional teams, including product managers, designers, and other engineers. Passion for learning new technologies and staying up to date with industry trends, best practices, and emerging technologies in web, data systems and AI. Ability to work in a fast-paced environment, manage multiple priorities, and adapt to changing requirements and deadlines. Proven ability to collaborate and contribute to a positive, inclusive work environment, fostering knowledge sharing and growth within the team.#MicrosoftAI Software Engineering IC6 - The typical base pay range for this role across the U.S. is USD $165,600 - $296,400 per year. There is a different range applicable to specific work locations, within the San Francisco Bay area and New York City metropolitan area, and the base pay range for this role in those locations is USD $220,800 - $331,200 per year. Certain roles may be eligible for benefits and other compensation. Find additional benefits and pay information here:https://careers.microsoft.com/us/en/us-corporate-payThis position will be open for a minimum of 5 days, with applications accepted on an ongoing basis until the position is filled.Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, citizenship, color, family or medical care leave, gender identity or expression, genetic information, immigration status, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran or military status, race, ethnicity, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable local laws, regulations and ordinances. If you need assistance with religious accommodations and/or a reasonable accommodation due to a disability during the application process, read more about requesting accommodations.