Full Stack Java Engineer

What you will work on

• The work spans the existing product and the new platform. How much of each you do will depend on where the team needs you and what you are good at. It includes:
• Integrations. Building and maintaining integrations with third-party payment providers and other partners: reading their APIs, working out what is feasible, building it, testing it and keeping it healthy in production.
• The new platform. Backend services and APIs in Java and Spring Boot, the frontend that sits on them, and the data model underneath. The build is delivered with an engineering partner under our technical direction; in-house engineers shape the design and review what gets built.
• The existing product. Customer-facing web pages, internal tools and the services behind them, in a codebase that is being modernised while it serves live customers.
• Quality and standards. Peer review, automated tests at unit, integration and end-to-end level, acceptance criteria, release notes. You contribute to our engineering standards and help hold everyone's work to them, including our partner's.
• AI-first practice. AI coding tools as your default for scaffolding, tests, documentation and proofs of concept, and the review and verification guardrails that let us do this safely in a PCI DSS Level 1 environment. Find repetitive work and automate it.

How we work

• PCI DSS Level 1 environment: peer review, test coverage, acceptance criteria and release notes are audit evidence, not ceremony.
• Java and Spring Boot today. We expect to introduce Kotlin on the new platform and want people who would enjoy that.
• A small, growing in-house team working with our Principal Architect and the engineers at our partner. DevOps and infrastructure are handled by a dedicated team; you need to be comfortable with pipelines and cloud deployment, not to own them.
• Sprints, tracked in Jira. We are modernising how engineering works here: better tooling, clearer standards, faster pipelines. You help set that up rather than inherit a finished machine.

Essential

• Typically 4+ years' professional software development, most of it in Java. Solid modern Java and object-oriented design, comfortable in older codebases too.
• Hands-on Spring Boot: REST APIs, Spring Security, Hibernate/JPA. Building and consuming APIs, integrating third-party services, handling failure modes in someone else's system.
• You have owned something: an integration, a service or a feature area where you were accountable for it working in production, not just for writing the code.
• Daily, practical use of AI coding tools with a clear discipline for verifying what they produce. You can explain what you check, how you catch a made-up API or a silent behaviour change, and when you do not trust the output.
• You read third-party API documentation carefully, spot the gaps early, and go to the provider's sandbox or support desk to resolve ambiguity rather than waiting to be told.
• Frontend you can ship to production. We care about fundamentals more than a particular framework: component-based UI and state management, how the browser and HTTP actually work, accessibility, performance, frontend security basics (XSS, CSRF) and testing. Experience with any mainstream framework (React, Angular, Vue or similar) and TypeScript.
• SQL and relational databases. Automated testing at unit, integration and end-to-end level (JUnit, Mockito, Playwright or similar). Git, Maven or Gradle.
• Comfortable with CI/CD pipelines, deploying to and supporting applications in the cloud (AWS or similar), and working with containers as a developer.
• Working understanding of distributed systems: services talking over a network, failure handling, idempotency, consistency trade-offs.
• Secure coding basics: input validation, secrets handling, dependency hygiene, and authentication and authorisation patterns (OAuth 2.0, OIDC, JWT).
• Clear written communication: your tickets, review comments and documentation will be read by colleagues outside engineering, our partner and our auditors.
• Degree in computer science or a related field, or equivalent practical experience.

Desirable

• Kotlin, or a strong interest in it.
• Payments, PSP or payment gateway integration experience.
• Experience building or operating multi-tenant SaaS.
• Experience working alongside, or reviewing the work of, an outsourced or offshore team.
• Experience in a regulated or high-availability environment (PCI DSS, financial services, healthcare).
• Messaging and event-driven patterns, caching, observability basics (metrics, tracing, structured logging).
• Exposure to real-time voice or telephony systems.
• A track record of automating repetitive engineering work: dependency upgrades, code generation, test fixtures.