Principal, Software Development Engineer

Your work days are brighter here. We’re obsessed with making hard work pay off, for our people, our customers, and the world around us. As a Fortune 500 company and a leading AI platform for managing people, money, and agents, we’re shaping the future of work so teams can reach their potential and focus on what matters most. The minute you join, you’ll feel it.

Not just in the products we build, but in how we show up for each other. Our culture is rooted in integrity, empathy, and shared enthusiasm. We’re in this together, tackling big challenges with bold ideas and genuine care. We look for curious minds and courageous collaborators who bring sun-drenched optimism and drive. Whether you're building smarter solutions, supporting customers, or creating a space where everyone belongs, you’ll do meaningful work with Workmates who’ve got your back.

In return, we’ll give you the trust to take risks, the tools to grow, the skills to develop and the support of a company invested in you for the long haul. So, if you want to inspire a brighter work day for everyone, including yourself, you’ve found a match in Workday, and we hope to be a match for you too.

The AI Model Serving team is the engine behind every production Workday agent and machine learning use case. We own the services that power all production AI workloads, serving as the gateway to vendor-hosted LLMs on GCP and AWS Bedrock and operating the model deployment platform where Workday hosts and scales its models. We host thousands of traditional ML models across sharded Ray Serve clusters, making us one of the heaviest users of Ray  platform handles approximately 2,000 requests per second and peaks at greater than 10,000 requests per second in our largest cluster.

We also provide a uniform interface for accessing models on Bedrock and Gemini, an evaluation platform for generative AI use cases, and the production model registry for Workday. In the year ahead, we are focused on making our uniform vendor interface more robust, scaling our architecture to support more than 20 agents going into production, improving cost governance, exploring hosting open‑source LLMs in our stack, evaluating a potential rewrite of the service in a different language for performance gains, and keeping pace with the rapidly evolving AI landscape.

Our culture is one of focus, camaraderie, and high performance. We are a friendly and dedicated group that takes pride in building and operating one of the most heavily used services  you are energized by working on infrastructure that sits at the heart of Workday's AI strategy, this is the team for you.

As a Principal Software Development Engineer on the AI Model Serving team, you will be a technical leader who helps shape the vision and direction of the platform alongside the engineering manager. You will play a central role in making critical design decisions, driving outcomes across the team, and setting a positive and inclusive team culture. In addition to the model serving platform, the team also owns the production model registry at Workday, and you will help guide its evolution and ensure it meets the needs of ML teams across the organization.

Your work will directly impact Workday's ability to serve AI at scale — from traditional ML models to the latest large language models powering Workday's agents.

• Help set the product vision for the AI Model Serving platform in partnership with the engineering manager, bringing a product-oriented mindset to infrastructure decisions.
• Lead the team technically by making critical design decisions that drive performance, reliability, and scalability across the platform.
• Design, implement, and maintain large‑scale systems that enable moving ML models to production.
• Write design documents to build consensus for new system components and enhancements to existing components.
• Evaluate and uptake new technologies made available within Workday and across the broader industry.
• Troubleshoot, improve, and scale continuous integration software pipelines.
• Develop relationships with software engineers, machine learning engineers, and data…