Principal Software Engineer

Would you like to help shape the UI platform that powers Windows experiences used by millions of developers and customers every day? The Windows Platform & Developer (WPD) Organization team builds and evolves the UI frameworks and APIs that first and third party developers rely on to create high quality desktop and enterprise line-of-business (LOB) applications.

We are looking for a Principal Software Engineer to help guide the next phase of Windows UI Platform’s evolution (including WinUI3) -modernizing the platform, improving fundamentals such as performance and reliability, and ensuring the developer experience meets the expectations of today’s desktop and enterprise app builders. This role blends strategic thinking with hands-on technical leadership and offers the opportunity to influence a widely used platform while staying close to real developer scenarios.

As a Principal Software Engineer, you will also focus on evolving WinUI into a modern, AI-native UI framework that remains competitive with SwiftUI while embracing a future where agents author a significant portion of application code. This requires rethinking WinUI as a declarative, composable, and semantically rich platform-one that is easy for web and SwiftUI developers to adopt, straightforward for AI agents to reason about, and powerful enough to enable dynamic, personalized user experiences at scale.

As a Principal Software Engineer, you will focus on

• AI-first developer experience: Design WinUI to be natively consumable by AI agents, with clear semantic models, stable abstractions, and predictable composition patterns that allow agents to author, refactor, and optimize UI code at scale.
• Seamless migration and adoption: Use AI-assisted tooling and compatibility layers to enable low-friction migration from legacy Windows UI stacks and SwiftUI on macOS, making WinUI a competitive and approachable choice for modern app developers.
• Declarative, dynamic UI foundation: Evolve WinUI into a truly declarative, state-driven framework that supports real-time personalization, adaptive layouts, and agent-driven UI mutation without sacrificing performance or reliability.
• Lowering the barrier for web and SwiftUI developers: Provide opinionated projections, simplified APIs, and familiar programming models that align with modern web and SwiftUI mental models, accelerating time-to-productivity on Windows.
• Future-proofing for AI-generated code: Architect WinUI so that a majority of UI code can be safely generated and maintained by AI agents-emphasizing composability, guardrails, testability, and runtime validation.

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

As a Principal Software Engineer, you will provide technical leadership across the Windows UI platform and work closely with engineering, program management, and partner teams.

Platform architecture and technical leadership

• Define and evolve the architectural direction for WinUI and related Windows UI components, ensuring designs are scalable, maintainable, and aligned with long-term platform goals.
• Review and guide architecture and design proposals across multiple teams, helping ensure consistency and technical quality.
• Act as a trusted technical advisor and sounding board for senior engineers and leaders working across UI, shell, graphics, input, and app model areas.

Modernization and quality of fundamentals

• Drive improvements in core platform fundamentals that matter to real desktop and LOB apps, including startup performance, memory usage, responsiveness, reliability, accessibility, and theming.
• Help identify and address common friction points that developers encounter when building or modernizing Windows desktop applications.

Developer experience and adoption

• Influence API design patterns, lifecycle models, diagnostics, and tooling to make the platform easier and more predictable to build on.
• Partner with PM and engineering teams to improve guidance and reduce friction for teams adopting newer UI technologies.
• Engage constructively with the developer community (including open-source communities where appropriate) to incorporate feedback and improve trust in the platform.

Mentorship and architecture culture

• Mentor senior ICs and aspiring architects, raising the overall bar for technical decision-making and design quality.
• Promote clear written specs, design reviews, and thoughtful technical storytelling across the organization.

Frontier mindset and AI-powered productivity

• Demonstrate a frontier-firm mindset: stay ahead of emerging UI platform trends (including AI-native UX patterns), challenge assumptions, and prototype quickly to de-risk big bets.
• Use modern AI tools responsibly to increase personal and team efficiency (e.g., drafting specs, summarizing design discussions, generating test ideas, exploring API surface options), while maintaining high standards for correctness, security, and privacy.
• Create reusable accelerators (prompts, templates, automation, reference implementations) that help teams move faster without sacrificing quality, reliability, accessibility, or maintainability.
• Model a culture of learning and iteration: share best practices, run lightweight demos, and help the organization adopt effective AI-assisted workflows.

Qualifications

Required/Minimum 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.

Additional or preferred qualifications

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 following specialized security screenings:

• Microsoft Cloud Background Check: This position will be required to pass the Microsoft Cloud background check upon hire/transfer and every two years thereafter.

Preferred Qualifications:

• Master'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#.
  • OR Bachelor's Degree in Computer Science or related technical field AND 15+ years technical engineering experience with coding in languages including, but not limited to, C, C++, C#.
  • OR equivalent experience.
• Significant hands-on experience building desktop or rich-client applications, with a solid focus on UX quality and system fundamentals.
• Depth in one or more UI frameworks for desktop or cross-platform development, such as WinForms, WPF, WinUI, SwiftUI, UIKit/AppKit, .NET MAUI, Avalonia UI, Qt, Uno Platform, Flutter, or Electron in firmly desired.
• Proficiency in C++ and/or C# (or comparable systems languages), with the ability to reason across framework, runtime, and OS layers.
• Experience navigating UI architecture tradeoffs involving performance, memory, rendering, input, threading, accessibility, and app lifecycle.
• Demonstrated ability to influence technical direction beyond your immediate team through design reviews, architectural guidance, or technical leadership.
• Experience modernizing or evolving an existing UI framework or large application platform.
• Experience designing developer-facing APIs or frameworks consumed by external teams or customers.
• Engagement with developer communities or open-source projects.
• Familiarity with Windows app models, interop scenarios, or graphics/composition pipelines.

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This 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.