Principal Software Engineer

Willow builds an Operational AI platform for the built world. The Principal Software Engineer will shape the technical direction and architecture of Willow’s platform while writing production code, setting engineering standards, improving security and reliability, and mentoring engineers.

Responsibilities:

• Own the architecture of complex, cloud-based systems on Azure, including containers, graph storage, LLMs, and a wide range of Azure services
• Stay hands-on: write production code and lead the design of new initiatives
• Design integrations with partners and customer systems that work smoothly across multiple companies
• Set technical standards, such as approved languages, libraries, Azure resources and framework versions, and make sure teams apply them consistently
• Raise the bar on code quality, observability and reliability across all of Willow’s software, including design and code reviews across teams
• Lead secure engineering practices and keep reducing vulnerabilities
• Work with Product to shape the product vision and explain trade-off decisions in terms of customer value
• Partner with Customer Engineering, Sales and Marketing to turn business needs into technical solutions
• Advise senior leadership on technical and product strategy
• Mentor senior and lead engineers
• Build a culture of transparency, knowledge sharing and continuous improvement
• Help teams use AI tools well in how they build, and in what we build
• Determine a path forward for Willow’s building topology graph storage that is secure, performant, cost-effective, and scalable, working closely with key Willow partners on cutting-edge solutions to difficult problems
• Own the features that make data in the graph available to the Willow Copilot AI platform and other parts of the platform
• Work daily with other developers at Willow to optimize the entire application platform, resolve issues, and design the architecture Willow needs to scale rapidly as we grow
• You design systems to optimize growth, performance, and cost
• You take pride in ownership and in your ability to deliver results and ship stable features
• You thrive when working with others, building consensus, and growing the entire team

Requirements:

• 10+ years of commercial software development, including senior or principal-level technical leadership
• Deep expertise in C# and modern .NET, plus working knowledge of TypeScript, React and Python
• A track record of designing, building and running distributed systems on Azure, using its PaaS services in production
• Strong command of design patterns and software architecture, and the ability to teach them to others
• Hands-on experience with CI/CD, infrastructure as code and DevOps practices
• Proven influence across teams and functions, with company-level technical decisions you can point to
• A security-first mindset, with experience leading secure development practices
• Clear writing and strong asynchronous communication with distributed teams across time zones
• Hands-on use of AI tools in your day-to-day work, and the ability to speak knowledgeably about how you use them
• IoT, digital twin or building-systems data (for example time series and graph data, or Azure Digital Twins / Microsoft Fabric)
• AI/ML in production: LLM platforms, MLOps pipelines, or AI features built into a SaaS product
• Data platforms such as Snowflake or Azure data services
• Pulumi or similar infrastructure-as-code tooling, plus Grafana or other observability tools
• Experience at a global start-up or scale-up