Principal Software Engineer

Microsoft • Redmond, WA

38d • Hybrid

About The Position

At Microsoft Edge, we keep people safe on the Internet. We are looking for a Principal Software Engineer who can develop improvements from fundamental coding architecture to user interventions, spanning both traditional web browser scenarios and the novel attack vectors unveiled with agentic browsing. You will work with partners in the browser, outside the browser, and even outside the company to ensure that the user maintains both security and peace-of-mind end-to-end, without any unnecessary compromises to the user's performance or experience. You will work on durable architectures that are self-monitoring and self-healing with minimal human intervention. You will identify longstanding patterns of problems and drive permanent solutions, even if that requires rethinking long-held assumptions. You will identify appropriate cases to use recent AI innovations, both to smooth the development process itself and in product scenarios. You will create automated testing and also telemetry systems which validate that our methods are still working despite a changing Internet landscape, and when they stop working, you will help to identify what changed and adapt to the new reality. You will work with the team, learning from them and especially spreading your learning to them, through means such as knowledge transfer, creating or sharing tools and techniques, giving high-quality code review feedback, or setting a great example through your coding patterns.
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.

Requirements

• 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++, Rust, C#, Java, JavaScript, or Python OR equivalent experience

Nice To Haves

• 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 Pytho OR 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 equivalent experience.
• 3+ years' systems engineering experience designing secure, high‑performance architectures across large client applications and delivering durable, end‑to‑end solutions.
• Proven ability to drive architectural changes and modernize complex/legacy codebases to improve performance, reliability, and maintainability.
• Experience influencing technical direction through reviews and cross-team collaboration.

Responsibilities

• Own and drive major security features and initiatives, such as new major feature techniques to cut off known in-market attacks, and novel defense-in-depth strategies to prevent or eliminate classes of attack vectors.
• Co-develop security for novel new major feature areas such as Agentic Browsing.
• Whenever possible, create designs without significant compromises to the user's experience. Any compromises that are unavoidable are mitigated to the maximum degree.
• Collaborate with partner teams to ensure end to end scenarios work well together, ensuring proper end-to-end testing, scalability, performance, success measures, and problem mitigation strategies are put together. Drives continued engagement with these partners.
• Applies and identifies best practices and shares information with other engineers for building code based on well-established methods and secure design principles while also applying best practices for new code development and formal validation of security invariants. Leads product development and scaling to customer requirements and applies best practices for meeting scaling needs and performance expectations and security promises.
• Leads by example across teams and mentors others to produce extensible, maintainable, well-tested, secure, and performant code used across products that adheres to design specifications. Leads efforts to continuously improve code performance, testability, maintainability, effectiveness, and cost, while learning about and accounting for relevant trade-offs. Identifies best practices and coding patterns and provides deep expertise in the coding and validation strategy. Creates and applies metrics to drive code quality and stability, appropriate coding patterns, and best practices. Identifies and anticipates blockers or unknowns during the development process, escalates them, communicates how they will impact timelines, and then leads efforts to identify and implement strategies and/or opportunities to address them.
• Leads efforts on using debugging tools, tests, logs, telemetry, and other methods, while respecting user privacy. Proactively lead verification of assumptions while developing code before issues occur across products in production. When regressions or other incidents happen, finds the root cause and takes steps to repair it permaentnly.
• Reviews product and test code to ensure it meets the team's high standards, and is an appropriate solution. Brings insight to code reviews to help improve code quality, coaching and providing feedback to develop other engineers' skills. Conducts code reviews in a timely fashion that helps accelerate the pace of development on the team. Considers diagnosability, reliability, testability, and maintainability when reviewing code, and understands when code is ready to be shared or delivered. Applies and reviews for coding patterns, security risks, compliance issues, and best practices in code reviews, providing feedback on code to drive adherence to best practices.
• Improve artificial intelligence (AI) tools and practices across the software development lifecycle. Takes responsibility for the content of their AI-generated content such as code or documents, and assist other members of the team to do the same. Experiments with AI tools and practices to improve their own capabilities, and provides recommendations on how to adopt them to other members of the team.

What This Job Offers

• Job Type: Full-time
• Career Level: Mid Level