OverviewAre you an established Software Engineer looking for a challenge and ready to tackle strategic cross-organization investments that span Microsoft AI, Office, and Windows to create web experiences for over 1B users and drive daily habit with users? Join us to innovate and create impactful experiences. We are looking for a highly skilled Principal Software Engineer (full stack) to join Microsoft AI – Copilot Discover team, who will provide technical leadership to key projects, and collaborate with frontend, backend and ML teams to maintain and deliver key features that will be used across multiple sites. You will develop strategy aligning with stakeholders and execute plans to successfully deliver on commitments. The ideal candidate will be an experienced full stack engineer with knowledge of ML, prompt tuning, modern front end web frameworks like web components/react, cloud-based architecture and services, caching, load-balancing, A/B experimentation. Your responsibilities will include designing, coding and operationalizing experience and services at hyper scale. MSN is a personalized content feed powering user experiences across Microsoft. Our mission is to empower every person on the planet to be informed, entertained, and inspired. With nearly 30 years of history, MSN has evolved into a premier content destination with high-quality content, AI-powered user-controlled personalization, and massive global reach. Over the past 4 years, AI and Machine Learning technologies have fueled massive growth, transforming MSN’s content moderation, personalization, and content entry points. Learn more about us here. 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.ResponsibilitiesDesign, build, and operationalize scalable ML and deep learning models using containers and orchestration platforms. Develop and refine LLM prompt strategies, evaluate performance, and continuously optimize model quality and user outcomes.Design, implement, and maintain responsive, accessible, and visually polished user interfaces and full-stack application features. Build and support front-end applications using TypeScript with frameworks such as React, NextJS, Web Components (or similar), and integrate them with robust back-end services. Develop scalable REST APIs and data access layers, ensuring efficient, secure, and reliable data flow between client and server. Collaborate with UX designers, backend engineers, and product teams to translate requirements, wireframes, and prototypes into functional, production-ready solutions. Optimize applications for performance, scalability, and cross-browser/cross-platform compatibility across the entire stack. Participate in code reviews, architectural discussions, and continuous improvement of development workflows and engineering standards. QualificationsRequired 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 PythonOR equivalent experience.Preferred Qualifications: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 PythonOR 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 PythonOR equivalent experience.5+ years of direct experience delivering, scaling, and owning highly successful and innovative content products.Proven experience developing and designing multi-tiered distributed services.Hands-on experience with deep learning model deployment and performance tuning.Experience working through full product cycles from initial design to final delivery.Hands-on experience with deep learning model deployment and performance tuning.Familiarity with DevOps practices, CI/CD, and infrastructure-as-code tools.Deep understanding of distributed systems, cloud-native architecture, and microservices.Solid communication and leadership skills with a track record of cross-team collaboration. Hands-on experience building production applications using React, Web Components or similar front-end frameworks. #MicrosoftAI #Software Engineer #ML engineer Software Engineering IC5 - The typical base pay range for this role across the U.S. is USD $142,800 - $274,800 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 $188,000 - $304,200 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.