Principal Software Engineer

Do you want to fine-tune OpenAI’s most advanced models on Azure — working with GPT-4.1, GPT-5, and beyond? From supervised fine-tuning (SFT) to reinforcement learning methods like DPO and others, this role puts you hands-on with the techniques shaping the future of AI.

On this team, you’ll play a key role in improving the performance and reliability of customizing some of the world’s most advanced AI models. You’ll gain hands-on experience with fine-tuning workflows, experimenting with reinforcement learning techniques, and applying advanced optimization strategies that directly impact product quality. You’ll also work directly with the training code, debug complex behaviors, and sharpen the skills that make cutting-edge models more reliable and effective. The models you help shape will power critical workloads at some of the world’s leading companies.

Microsoft’s mission is to empower every person and every organization on the planet to achieve more, and we’re dedicated to this mission across every aspect of our company. Our culture is centered on embracing a growth mindset and encouraging teams and leaders to bring their best each day. Join us and help shape the future of the world.

Preferred:

• 10+ years of experience writing production code in building internet scale services and distributed systems. 
• Engineering knowledge of machine learning systems and data pipelines.
• Experience mentoring other developers, working partners and being a team player.
• Excellent communication and presentation skills

Required:

• Ability to debug, read code and work in a large codebase.

Microsoft is an equal opportunity employer. All qualified applicants will receive consideration for employment without regard to age, ancestry, color, family or medical care leave, gender identity or expression, genetic information, marital status, medical condition, national origin, physical or mental disability, political affiliation, protected veteran status, race, religion, sex (including pregnancy), sexual orientation, or any other characteristic protected by applicable laws, regulations and ordinances. If you need assistance and/or a reasonable accommodation due to a disability during the application or the recruiting process, please send a request via the Accommodation request form.

Benefits/perks listed below may vary depending on the nature of your employment with Microsoft and the country where you work.

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.

Responsibilities: 

Coding 

• 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 (e.g., leveraging state-of-the-art generative artificial intelligence [GenAI], approaches to source code organization, naming conventions) 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, and proactively leads verification of assumptions while developing code before issues occur across products in production. Leverages minimal telemetry data, triangulates issues, and resolves with minimal iterations. Leads incident retrospectives to identify root causes of

  problems, the implementation of repair actions, and the identification of mechanisms to prevent incident recurrence. Proactively applies least-access principles, uses logging, telemetry, and other appropriate mechanisms to investigate issues while retaining privacy and security, and drives those practices across the team.

• Reviews product code and test code to ensure it meets team standards, contains the correct test coverage, and is appropriate for the product or solution area. 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. Uses automated source code analysis tools that are incorporated into the build/development process.

Design

• Owns and leads efforts and discussions for the architecture of aspects of complex products/solutions (e.g., design, cost). Leads the testing and exploration of various design options across a set of complex product/solution scenarios, ensuring the strengths and weaknesses of each option are outlined and making recommendations for which design option is best. Creates proposals for architecture and design documents, and leads testing of hypotheses and proposed complex solutions. Shares and acts on findings from investigations, owns design decisions, and oversees the less experienced team members. Leads the development of design documents that support user stories and other product requirements. Evaluates new technologies to solve classes of problems, and determines how to integrate these technologies within existing systems. Leads design discussions with the team and shares findings/learnings from investigations, holding ownership for design decisions. Leads efforts to ensure system architecture and individual designs meet performance, scalability, resiliency, disaster recovery, cost of goods sold (COGS), and other requirements and expectations. Upholds Microsoft's standards of security, privacy, and other compliance requirements and expectations. Understands and coaches less experienced engineers on the importance of building solutions that expand upon the work of others. Leads the refinement of products through data analytics, and makes informed decisions in engineering products through data integration. Reviews complex designs/architectures within and across teams to provide recommendations for improvements.
• Mentors others on and independently creates a clear test strategy that ensures solution quality, prevents regression from being introduced into existing code. Mentors others on and independently ensures test plans incorporate security testing to validate security invariants (including negative cases). Leads adding new tests to cover gaps, deleting or fixing broken tests, and improving the speed, reliability, and defect localization of the overall test suite. Mentors others on, and builds testable code and considers testability during design for a set of solutions. Understands the different types of tests that can be done on a particular system (e.g., unit tests), and maintains up-to-date understanding of testing architectures used both across Microsoft and across the industry, and applies them across the architecture as appropriate. Designs and executes plans for redesigning or rearchitecting difficult or untestable sections of code for a set of solutions. Leverages artificial intelligence (AI) tools for test automation.

Engineering Excellence

• 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.
• Remains current by investing time and effort into being informed staying abreast of current developments. Proactively seeks new knowledge, evaluating new trends, technical solutions, and patterns, assessing how to adapt them to current problems, and shares knowledge with other engineers. Conducts learning and literary sessions to raise awareness on relevant engineering design principles (e.g., security, testability, performance, scalability, accessibility, product knowledge).