Principal Software Engineer, Copilot Discover Fullstack

Are 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.

Design, 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.

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. Other Requirements: Ability to meet Microsoft, customer and/or government security screening requirements are required for this role. These requirements include but are not limited to the