Principal Software Engineer

• Own the platform’s technical direction, frontend architecture and delivery, and take part in the key design decisions across the whole product, including the backend and integrations
• Lead architectural design and keep technical consistency across the frontend, backend and integrations
• Set the technical bar: define what good code, design and reviews look like, lead design discussions, code reviews and architecture sessions, and record decisions
• Shape and design the backend-for-frontend service with backend engineers, covering API contracts, authentication, role-based access and background processing
• Design extensible patterns so new evaluation types, workflows and partner integrations fit cleanly as the platform grows into a shared service
• Lead the implementation of components that span multiple services and modules, working across the stack from development to infrastructure
• Make the platform reliable at scale, with no lost expert work and fast, stable performance for hundreds of concurrent users
• Diagnose and resolve complex technical issues across distributed systems, and complete the most complex bug fixes
• Design and maintain data models that support both operational and analytical use cases
• Build relationships with other engineering teams to understand their needs and solve their pain points, and automate processes that help them
• Work directly with evaluation teams, data scientists and end users to turn requirements into clear, reliable technical plans
• Serve as the primary technical point of contact for partner teams and external technology resources
• Drive an AI-first engineering practice, continuously improve development processes and lead knowledge sharing across the team
• All other duties as assigned
  

• 10+ years of software engineering experience, with at least 7 years building large web applications on the frontend
• BS in Engineering or Computer Science, or equivalent experience required; advanced degree preferred
  

• Expert in React (18+), TypeScript and modern JavaScript, with a track record of leading frontend architecture for production applications
• Deep understanding of scalable frontend architecture, including routing and data loading, server-state management, performance at scale, component libraries and design systems
• Working knowledge of Node.js backends, ideally NestJS, including REST API design, backend-for-frontend patterns, OIDC and session-based authentication, and role-based access
• Deep understanding of distributed system design, data modelling and performance tuning, including relational databases such as PostgreSQL
• Expert in test-driven development and CI/CD, with hands-on use of Vitest or Jest, Testing Library, Playwright and quality gates in CI
• Practical knowledge of Vite, Yarn, Docker, nginx, AWS infrastructure as code and CI/CD with GitHub Actions
• Hands-on experience with modern AI tools such as Claude or Codex, and an AI-first approach to delivering high-quality software
• Solid knowledge of architectural principles, with the ability to explain trade-offs clearly and make decisions that hold up over time
• Ability to drive technical outcomes independently, from problem definition to deployment
• Expert in Agile or Kanban delivery, with strong planning, prioritisation and change management across multiple teams
• Proven ability to partner with and lead internal and external technology resources to solve complex business needs
• Strong communication and presentation skills for a wide audience, from engineers to senior leadership and non-technical users

• Familiarity with LLM evaluation concepts such as rubric-based metrics, LLM-as-a-judge, inter-rater agreement and adjudication
• Experience building internal platforms or developer-facing tooling used by other teams
• Knowledge of observability best practices, including metrics, logs, alerts and real-user monitoring
• Experience with streaming UIs (server-sent events) and data-heavy dashboards
• Working knowledge of specification-driven development (SDD) and agentic, AI-driven development workflows
  

Libra is an internal evaluation platform within Elsevier’s Search & AI Platform. The Evaluation Team builds platform capabilities that can support multiple Elsevier products, particularly around evaluating and enabling AI-driven use cases.

As Principal Software Engineer you will be the platform’s lead technical voice. You will own the frontend architecture and delivery, help shape the backend and integrations across the product, and set the technical bar for a distributed team. You will lead large multifunctional development work, solve the hardest technical problems, write complex production code and act as the senior source of expertise for the product. You will also give management sizing, roadmap and budget recommendations.

A global leader in information and analytics, we help researchers and healthcare professionals advance science and improve health outcomes for the benefit of society. Building on our publishing heritage, we combine quality information and vast data sets with analytics to support visionary science and research, health education and interactive learning, as well as exceptional healthcare and clinical practice. At Elsevier, your work contributes to the world's grand challenges and a more sustainable future. We harness innovative technologies to support science and healthcare to partner for a better world.

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Are you passionate about shaping the technical direction of a modern, AI-enabled platform and leading architectural decisions that drive long-term impact?

Do you enjoy working across frontend, backend, and infrastructure to deliver scalable, reliable software that solves complex business challenges for engineering teams and end users?

We promote a healthy work/life balance across the organisation. We offer an appealing working prospect for our people. With numerous wellbeing initiatives, shared parental leave, study assistance, and sabbaticals, we will help you meet your immediate responsibilities and your long-term goals. 1

Working flexible hours - flexing the times when you work in the day to help you fit everything in and work when you are the most productive. 1