Senior Full Stack Engineer

Requisition Number: 2360247
Optum is a global organization that delivers care, aided by technology to help millions of people live healthier lives. The work you do with our team will directly improve health outcomes by connecting people with the care, pharmacy benefits, data and resources they need to feel their best. Here, you will find a culture guided by diversity and inclusion, talented peers, comprehensive benefits and career development opportunities. Come make an impact on the communities we serve as you help us advance health equity on a global scale. Join us to start Caring. Connecting. Growing together.
Role Summary:
The Senior Full Stack Engineer is a hands-on senior individual contributor who designs, builds, tests, deploys, and supports modern software solutions across the full stack. This role is expected to work deeply in backend services, frontend applications, APIs, cloud infrastructure, and engineering quality practices while helping the team solve complex technical problems. Depending on the business area, the role may also contribute to AI/LLM-enabled workflows, healthcare interoperability, conversational systems, data-intensive services, or cloud-native application modernization.
Careers with Optum offer flexible work arrangements and individuals who live and work in the Republic of Ireland will have the opportunity to split their monthly work hours between our Dublin office and telecommuting from a home-based office in a hybrid work model.
Primary Responsibilities:

• Lead the design, development, and deployment of backend services and APIs that power AI/ML and GenAI pipelines, with a focus on scalability, reliability, and deterministic behaviour in production systems
• Architect and implement API-first, microservice-based platforms using Node.js (TypeScript) and Python to support model inference, orchestration, retrieval (RAG), and decision workflows
• Build and maintain AI pipeline infrastructure, including model execution services, prompt orchestration, feature extraction, and integration with vector databases and data platforms
• Design and implement integrations with Electronic Health Record (EHR) systems using FHIR standards, enabling secure, auditable exchange of clinical data to support AI-driven use cases
• Develop and enforce FHIR-compliant APIs, validation layers, and data transformation services to ensure interoperability, data quality, and guideline-aligned behaviour across clinical workflows
• Collaborate closely with data science, clinical informatics, product, and platform teams to translate clinical and business requirements into robust backend architectures supporting AI-enabled applications
• Implement and maintain infrastructure as code (IaC) and CI/CD pipelines to enable secure, scalable, and repeatable deployments of AI backend services across environments
• Ensure high availability, performance, observability, privacy, and security of backend systems, including appropriate handling of PHI and alignment with healthcare compliance requirements

You will be rewarded and recognized for your performance in an environment that will challenge you and give you clear direction on what it takes to succeed in your role, as well as providing development for other roles you may be interested in.
Required Qualifications:

• Bachelor's degree in Computer Science, Software Engineering, Information Technology, Engineering, or a related technical field, or equivalent practical experience
• Proven solid experience in professional software engineering, including full stack application development
• Demonstrated solid experience in backend technologies such as Java, Spring Boot, Spring Security, J2EE, Python (including asynchronous service development), or Node.js with TypeScript
• Proven experience building and maintaining APIs, microservices, or distributed systems
• Demonstrated solid experience in frontend engineering using React or Angular, TypeScript, and modern JavaScript frameworks and UI libraries
• Demonstrated solid experience designing and implementing REST APIs and service integrations
• Proven experience working with cloud platforms such as Azure or AWS
• Proven experience with containerization and orchestration technologies, including Docker, Kubernetes, or AKS
• Proven experience working with CI/CD pipelines, Git based workflows, build automation, and release engineering
• Demonstrated solid knowledge of testing practices, including unit, integration, API, regression, and automated testing strategies
• Demonstrated experience working with integration standards such as FHIR, HL7, SSO, JWT, or SAML

Preferred Qualifications:

• Proven experience working with healthcare platforms, healthcare data, or healthcare workflow modernization
• Proven experience in AI or LLM application development, evaluation, or operationalization
• Demonstrated experience working with RAG pipelines, tool calling, prompt regression testing, or agent orchestration frameworks
• Proven experience with modern frontend practices, including React 18, streaming UI patterns, Storybook, and component driven development
• Proven experience with test automation frameworks such as Jest, Cypress, pytest, or Playwright
• Proven experience mentoring engineers and influencing engineering best practices
• Proven experience working with infrastructure as code, including Terraform or equivalent tools
• Demonstrated experience working with tools and libraries such as Pydantic, LangChain, LangGraph, vector stores, embeddings, and prompt or version management

Please note you must currently be eligible to work and remain indefinitely without any restrictions in the country to which you are making an application. Proof will be required to support your application.
At UnitedHealth Group, our mission is to help people live healthier lives and make the health system work better for everyone. We believe everyone-of every race, gender, sexuality, age, location and income-deserves the opportunity to live their healthiest life. Today, however, there are still far too many barriers to good health which are disproportionately experienced by people of color, historically marginalized groups and those with lower incomes. We are committed to mitigating our impact on the environment and enabling and delivering equitable care that addresses health disparities and improves health outcomes - an enterprise priority reflected in our mission.
Diversity creates a healthier atmosphere: Optum is an Equal Employment Opportunity employer and all qualified applicants will receive consideration for employment without regard to gender, civil status, family status, sexual orientation, disability, religion, age, race, and membership of the Traveller community, or any other characteristic protected by law. Optum is a drug-free workplace. © 2026 Optum Services (Ireland) Limited. All rights reserved.
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