Principal Full Stack Software Engineer in Cardiff

All the relevant skills, qualifications and experience that a successful applicant will need are listed in the following description.

Salary to £80k, possibly higher for their Unicorn candidate. Role can be based remotely, as long as you can occasionally travel to London for client work (travel expenses paid) - approximately once a month.

NB: Please only apply if you are a UK National & UK passport holder, have resided in the UK for the past 5 years and are prepared to go through UK SC Security Clearance. Proof of ID will be required prior to interview.

This role is with a growing technology consultancy. This is a hands-on principal engineering role: architecture ownership across multiple services, technical leadership across teams, and direct contribution to engineering standards and hiring. The successful candidate will be writing code as well as setting direction - this is not a purely architectural or management position.

Current delivery is a Java/Spring Boot microservices platform on AWS EKS, with a Next.js frontend and Camunda-based process orchestration.

Essential Experience:

• Experience level: 10+ years minimum, principal or staff grade equivalent.
• Backend and cloud:
• Java 17 or 21, at expert level - modern language features
• Spring Boot in depth: security, transaction management, async/reactive
• Microservices architecture design - has designed services from scratch
• Kubernetes and Docker in production (not local development use)
• AWS, hands-on: EKS, Lambda, S3, RDS, EventBridge
• CI/CD pipeline ownership
• Automated testing discipline: JUnit, Mockito, integration testing, TDD or BDD
• Frontend:
• Held a lead or tech lead role on frontend development in React. Leadership must have been over React work itself.
• Understands and has implemented FFE/BFE separation - the split between the presentation layer (components, styling, client state) and the frontend's own server-side tier (data aggregation for the UI, session and auth handling, server-side rendering, API route composition).
• Leadership:
• Architecture ownership across multiple systems
• Cross-team technical leadership
• Track record of influencing engineering standards, technology choices, or hiring
• Evidence of growing other engineers
• Security clearance: UK SC clearance required. Active clearance strongly preferred; eligible candidates considered - must be a UK national with 5+ years continuous UK residency.

Desirable:

• Camunda 8 / BPMN process orchestration
• Next.js specifically (App Router, server components, route handlers)
• Terraform or other infrastructure-as-code, to module-authoring level
• React Native or equivalent building native mobile from a React codebase
• Design system or component library ownership
• Consultancy or client-facing delivery background
• Open-source contributions, conference talks, or published technical writing
• Polyglot beyond Java

NB: for non-UK Citizens; we cannot accept applications from anyone requiring sponsorship (now or in the future) for UK permanent employment. If you are utilising a work visa, this must allow you to work in the UK unrestricted for at least the next 5 years.