Principal API Architect, Product Engineering – Agent‑Ready APIs

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.

About the Team

Product Engineering builds the end‑to‑end product experiences that Workday customers use. Many of these experiences are now powered by agents and AI, which depend on a strong API foundation. This role sits in Product Engineering but operates across product pillars. You will work closely with Product Engineering teams as well as partner organizations. You will shape the API foundation, architecture and operating model that makes it easy for Product Engineering to build agent‑ready, high‑quality APIs.

About the Role

We are seeking a Principal-level API Architect in Product Engineering to lead our API strategy for agentic, product-centric, and integration-heavy scenarios. You will own the API architecture vision for Product Engineering, set standards across API design and product integration patterns, and partner with engineering and product leaders to make them real.

The ideal candidate has deep hands-on experience designing and building products end to end, from product and domain modeling through backend implementation, API design, and production operations. They should understand how product functionality is translated into scalable services and well-modeled API endpoints, and they should be comfortable working across large-scale systems using strong object-oriented modeling and software design principles.

In this role, you will:

• Define and evolve the API architecture, standards, and review processes that guide how Product Engineering teams design and deliver APIs.

• Partner with product and platform leaders to shape the operating model, including API champions across product pillars and a clear intake/prioritization path for API needs.

• Help Product Engineering teams think through product design, domain modeling, service boundaries, and API endpoints that support end-to-end product functionality.

• Ensure APIs are designed not only as technical interfaces, but as durable product contracts that reflect clear product capabilities, domain concepts, and customer use cases.

What you’ll do

• Define the API architecture and governance model for Product Engineering, spanning REST, GraphQL, SOAP, and emerging integration models used by Workday agents and products.

• Partner with product and engineering teams to design product capabilities end to end, including domain models, service boundaries, object models, API endpoints, and integration flows.

• Translate product requirements and user workflows into scalable backend services and well-structured API contracts.

• Establish and maintain API standards:

  • OpenAPI contract guidelines, review and approval process.
  • Resource modeling, naming and pagination conventions.
  • Authentication/authorization and multi‑tenant patterns.
  • Error handling, retry semantics, and idempotency guidelines.
  • Versioning and deprecation policies.

• Partner with Product Engineering leaders and “API champions” in each product area to:

  • Shape their API roadmaps.
  • Identify gaps or duplication.
  • Drive convergence on shared patterns and building blocks.

• Define reference architectures and patterns for:

  • Agent‑ready APIs and orchestration patterns used by the Agent Factory.
  • Data‑centric APIs, including how Product Engineering safely exposes data via Data Cloud / SQL projections.
  • Latency and observability standards across the end‑to‑end request path.

• Lead critical cross‑team API design reviews and act as the tie‑breaker on contentious or high‑impact design decisions.

• Work closely with platform partners to ensure Product Engineering’s needs are represented and that platform capabilities are consistently applied.

• Shape and help run a single, transparent intake and prioritization process for key Product Engineering API investments.

• Evaluate build/borrow/buy options for tools that help Product Engineering design, test, and operate APIs (including contract testing, catalogs, MCP/Data Cloud connectors, and developer tooling).

• Mentor senior engineers and managers on API architecture, distributed systems, and integration best practices; build communities of practice across Product Engineering.

• Communicate the API vision and status to senior stakeholders and help influence product and resourcing decisions.

About You

Basic Qualifications

• 12+ years of experience building large-scale, mission-critical backend systems and APIs; with responsibility for cross-team or organization-wide API/platform architecture

• 7+ years of experience in software engineering, with hands-on experience in object-oriented modeling and software design concepts such as domain modeling, abstraction, encapsulation, extensibility, and maintainable service design

• 5+ years of experience designing API endpoints that expose product functionality clearly, consistently, securely, and at scale, with proven track record of setting and driving technical standards across multiple teams.

• Deep hands-on experience with object-oriented modeling and software design concepts, using Java, TypeScript or Python to build maintainable web services and APIs across REST, SOAP, JSON, XML,and Swagger/OpenAPI.

Other Qualifications

• Experience leveraging AI‑assisted code generation and review tools (e.g., Cursor, Claude Code, GitHub Copilot) to improve development speed and quality.

• Strong expertise in distributed systems and cloud architectures, including high‑throughput, low‑latency services, horizontal scaling, and fault‑tolerant design.

• Extensive experience with edge and gateway patterns (routing, auth, throttling, rate limiting, transformation, multi‑tenant concerns).

• Demonstrated leadership in API governance: standards definition, contract review, documentation, and lifecycle management.

• Experience designing or evolving observability for APIs (metrics, tracing, logging) and using that data to define and monitor SLOs.

• Familiarity with agentic AI use cases and patterns for integrating LLMs/agents with enterprise APIs

• Experience with data platforms and analytical stores (such as Data Cloud or equivalent) and designing APIs that expose data safely and efficiently.

• Ability to collaborate and influence across Product Engineering, platform teams, and business stakeholders.

• Excellent written and verbal communication skills; able to articulate complex technical topics in simple, compelling terms.

• Passion for growing others: mentoring staff‑level engineers, supporting managers, and building a strong API culture within Product Engineering.

• Growth mindset and comfort working in evolving spaces where the operating model is still being defined.

• Bachelor's degree in a relevant field such as Computer Science or Engineering, or equivalent practical experience

Workday Pay Transparency Statement (For EU Locations Only)

Listed below is the base salary range applicable to this position. Workday pay ranges (and the precise pay offered to the successful candidate) are based on a number of objective criteria such as relevant experience and skills, and educational qualifications, level of responsibility, demands of the role, work location and business need. As a part of the total compensation package, this role may be eligible for the Workday Bonus Plan or a role-specific commission/bonus, as well as annual refresh stock grants awarded by Workday Inc. For more information regarding Workday’s comprehensive benefits, please click here.

Primary Location Base Pay Range: €104,000 EUR - €156,000 EUR Ireland

Our Approach to Flexible Work

With Flex Work, we’re combining the best of both worlds: in-person time and remote. Our approach enables our teams to deepen connections, maintain a strong community, and do their best work. We know that flexibility can take shape in many ways, so rather than a number of required days in-office each week, we simply spend at least half (50%) of our time each quarter in the office or in the field with our customers, prospects, and partners (depending on role). This means you'll have the freedom to create a flexible schedule that caters to your business, team, and personal needs, while being intentional to make the most of time spent together. Those in our remote "home office" roles also have the opportunity to come together in our offices for important moments that matter.

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Workday is an Equal Opportunity Employer including individuals with disabilities and protected veterans.

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