Senior Full-Stack Engineer

A senior, hands-on engineer who builds modern front ends and Java back ends on AWS within a globally distributed team in a regulated payments environment, using AI as a daily tool to deliver better software faster, with human judgement firmly in charge.The OpportunityWe are hiring a Senior Full-Stack Engineer to build customer-facing payments applications. You will work across the whole stack: front-end interfaces, Java services and APIs, and delivery to an AWS-hosted platform. Money movement leaves little tolerance for defects, security gaps or uncontrolled change, so this is a role for someone who has delivered under those conditions.You will be a senior, hands-on member of a globally distributed team: owning features from idea to production, making sound design decisions and raising the quality of the work around you through code review and example. You will work closely with product, design and the Lead Full-Stack Engineer. This is also a role for someone who has made AI part of how they deliver software. We expect engineers to use AI assistants and agentic tooling routinely for design exploration, code, tests, refactoring, documentation and debugging, and to be honest about where it helps and where it does not. The standard is unchanged: you remain accountable for every line that ships, and speed gained from AI must never be paid for in quality, security or maintainability.You will help the team get more from AI: share techniques that work and show what good looks like, within the guardrails that a regulated environment requires.Key ResponsibilitiesProduct deliveryDeliver features end to end: refine requirements with product and design, build across front end and back end, release and monitor in production.Build accessible, performant front-end applications using a modern framework, with well-structured components, state management and a maintainable design system.Design and implement Java services and APIs (REST and, where appropriate, event-driven) with clear contracts, sound data models and robust error handling.Work with legacy and adjacent code, including PHP and mobile (Flutter) where the product requires it, and help modernise it pragmatically.AI-enabled engineeringUse AI assistants and agentic tools daily to accelerate design, coding, test generation, code review, refactoring, debugging and documentation.Review AI-generated output with the same rigour as any code: verify correctness, security, licensing and fit with the architecture before it merges.Share what works: prompts, repository conventions, context files and guardrails that improve results across the team.Contribute to evaluating new AI tools, measuring their effect on lead time, defect rates and developer experience rather than relying on impressions.Where the product calls for it, integrate AI capabilities (for example LLM-backed features), including evaluation, cost control and safe handling of data.Quality and reliabilityWrite automated tests at the right levels (unit, integration, contract and end to end) and treat a failing pipeline as a team priority.Build and maintain CI/CD pipelines and infrastructure as code on AWS with the platform team, favouring small, frequent, reversible releases.Instrument services with logging, metrics and tracing, and take part in incident response and blameless reviews.Apply secure engineering practice throughout: input validation, authentication and authorisation, dependency and secrets hygiene, and privacy by design.Collaboration and CraftTake part in design discussions, write concise technical decisions and review colleagues' code constructively.Share knowledge through pairing, documentation and short internal sessions, and support less experienced engineers informally.Communicate trade-offs plainly to non-technical colleagues, and raise risks early.Payments and regulated deliveryBuild payment journeys that are correct by design: idempotent operations, clear transaction states, reconciliation and full auditability.Apply the controls that apply to the business (for example PCI DSS, strong customer authentication, sanctions and fraud screening integrations, and FCA operational resilience expectations) without slowing delivery unnecessarily.Work with security, risk and compliance colleagues and maintain audit-ready evidence for changes and releases.Essential experience and capabilitiesExperience7+ years building and running production web applications, with a track record of shipping features end to end.Commercial experience in both front end and back end, and comfort moving between them as the work demands.Experience building systems where correctness, security and availability carry financial or regulatory consequences.Demonstrable use of AI to deliver software: able to describe concrete workflows, the results achieved and the limits encountered.Technical depthJava: solid back-end engineering in modern Java (17 or later) with a mainstream framework such as Spring Boot, including API design, persistence, concurrency and testing.Front end: strong command of at least one modern front-end framework in production (for example Angular, Vue or React) and TypeScript, including component design, state management, testing, accessibility and performance, and the ability to become productive quickly in ours.Data: relational database design and query optimisation (for example PostgreSQL or MySQL), with working knowledge of caching and messaging.AWS: working knowledge of core services (for example EC2/ECS, Lambda, S3, RDS, IAM, CloudWatch) and how applications are built, deployed and observed on them.Engineering practice: version control and code review, CI/CD, automated testing at several levels, and infrastructure-as-code awareness.Security and quality: knowledge of common web vulnerabilities (such as the OWASP Top 10) and how to prevent them.AI-assisted delivery: fluent use of at least one leading AI coding assistant or agentic tool, with disciplined verification of its output.BehavioursTakes ownership of outcomes, not only tasks, and cares about the customer experience.Works well independently within a distributed team, and shares knowledge generously through constructive code review and documentation.Sound judgement about when to trust, adapt or discard AI output, and about when to follow a control, improve it or escalate.Communicates clearly in writing, which is the basis of effective asynchronous work across time zones, and explains trade-offs plainly to non-technical colleagues.Curious and pragmatic: learns quickly, prefers simple solutions and shares what they learn.Desirable experiencePayments domain knowledge: card and account-to-account flows, remittance, reconciliation, PCI DSS scope management and screening integrations.PHP: experience maintaining or modernising PHP applications (for example Laravel or Symfony), including migration towards Java services.Flutter: experience building and shipping cross-platform mobile applications.Experience with more than one front-end framework, including React.Experience building AI-powered product features, such as retrieval-augmented generation, LLM integration, evaluation and prompt management, including cost and latency management.Experience with agentic development workflows.Serverless and container experience on AWS (Lambda, Fargate, EKS) and infrastructure as code (Terraform or AWS CDK).Event-driven architecture and messaging (for example SQS, SNS, Kafka).Experience working with regulators, auditors or external assessors.