Principal API Architect (Product Engineering - Agent-Ready APIs)

Workday; Ireland; On-site; EUR 120,000 - 180,000; Full time

Job summary

Workday is seeking a Principal API Architect in Product Engineering to lead API strategy for agentic, product-centric APIs and integrations. You will own standards across REST, GraphQL, SOAP, and emerging models, shaping product contracts and durable API capabilities across teams.

You will collaborate with product and platform leaders to define roadmaps, intake processes, and architectural reference models.

Qualifications

• 5+ years designing API endpoints that expose product functionality clearly and securely.
• 7+ years of software engineering, with OO modeling and design concepts.
• 12+ years building large-scale backend systems and API/platform architecture.
• Experience with data platforms and APIs that safely expose data.

Responsibilities

• Define and evolve the API architecture, standards, and review processes.
• Lead cross-team API design reviews and resolve high-impact decisions.
• Mentor senior engineers and build communities of practice.
• Shape API roadmaps with product pillars and identify gaps/duplication.
• Evaluate tools for API design, testing, and observability; drive best practices.

Skills

API architecture

Distributed systems

REST/GraphQL/SOAP

Java/TypeScript/Python

Mentoring

Leadership

API governance

Education

Bachelor's in CS or Engineering

Tools

OpenAPI

Data Cloud

Cursor

GitHub Copilot

Job description

• 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

• 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

• 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

• 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

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. 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. 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. Experience leveraging AI-assisted code generation and review tools (e.g., Cursor, Claude Code, GitHub Copilot) to improve development speed and quality. 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. 12+ years of experience building large-scale, mission-critical backend systems and APIs; with responsibility for cross-team or organization-wide API/platform architecture. Experience with data platforms and analytical stores (such as Data Cloud or equivalent) and designing APIs that expose data safely and efficiently. Passion for growing others: mentoring staff-level engineers, supporting managers, and building a strong API culture within Product Engineering. 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. Strong expertise in distributed systems and cloud architectures, including high-throughput, low-latency services, horizontal scaling, and fault-tolerant design. Ability to collaborate and influence across Product Engineering, platform teams, and business stakeholders. 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. Excellent written and verbal communication skills; able to articulate complex technical topics in simple, compelling terms. 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.