Principal Software Engineer - Full Stack (Java)

• We’re transforming our ATM network with secure, resilient, cloud-native engineering at scale.
• You have deep Java, Spring Boot, AWS and full-stack expertise with Principal-level leadership.
• Together we will shape architecture, modernise legacy systems and accelerate AI-powered engineering.

Do work that matters:

Join the Customer Service Network Domain as a Principal Software Engineer and help reshape the technology powering one of the most critical parts of the customer experience: our ATM network. You’ll take a leading role in a major three-year transformation spanning ATM software, routing and switching, reconciliation, real-time data and cash-management capabilities, including a greenfield ATM switching platform and the move towards a cloud-native architecture. This is deep engineering work at scale, to create platforms that are secure, maintainable and built for production from day one. You’ll have the opportunity to define the target architecture rather than simply reproduce the past, applying strong engineering judgement to determine what should be modernised, simplified or completely reimagined.

As a Principal Engineer, you’ll bring technical leadership to some of the domain’s hardest problems, from designing resilient cloud infrastructure and integrating a new Java-based ATM switch to unravelling complex legacy estates. You’ll champion Terraform, quality engineering, fail-safe design, REST APIs and modern observability patterns, while helping teams build clear ownership across interconnected systems. AI is also becoming part of the engineering toolkit, creating opportunities to use LLMs, knowledge graphs and agentic approaches to accelerate reverse engineering, uncover requirements, prototype solutions and improve the developer experience. More than delivering individual components, you’ll influence engineering direction across the domain, mentor other engineers and turn a highly interconnected technology landscape into simpler, safer and more adaptable services for customers.

See yourself in our team:  

 You’ll join our Customer Service Network team, working within Assisted Technology to reimagine how our branch colleagues support customers. We’re bringing together engineering, customer journeys and colleague experiences to move beyond disconnected technology and create simpler, more connected ways to serve customers. Our team is building capabilities including intelligent concierge experiences, agentic appointment booking, customer-intent capture, skills matching and smarter branch operations, all with the ambition of helping colleagues serve customers faster and reducing the time customers spend waiting.

We’re a team that enjoys solving complex problems together and shaping solutions where the answers aren’t always obvious. With significant greenfield engineering ahead of us, you’ll work across modern technology and AI-enabled engineering, while helping influence our architecture, engineering practices and technical direction. You’ll have the space to challenge ideas, share your expertise and help us build experiences that make a meaningful difference for both our customers and the colleagues who serve them.

We’re interested in hearing from people who: 

• Bring Principal Engineer-level systems thinking and end-to-end architecture expertise, connecting complex customer journeys, platforms, data, dependencies and technical requirements across highly interconnected environments.
• Have deep Java and Spring Boot expertise combined with genuine full-stack engineering breadth, ideally spanning TypeScript, React, Next.js and Node.js, with the versatility to work effectively across modern and legacy technology stacks.
• Have designed and delivered cloud-native, distributed systems at scale, encompassing APIs, event-driven architecture, SDKs, data, CI/CD, infrastructure as code, observability, resilience and complex integrations.
• Can translate ambiguous business and domain challenges into clear architecture and engineering direction, making pragmatic, product-led technical trade-offs across multiple engineering teams.
• Have led safe, large-scale modernisation of complex legacy environments, reducing technical debt and simplifying architecture while protecting reliability, customer experience and delivery momentum.
• Bring strong integration engineering experience, designing and evolving reliable integrations across complex, interconnected platforms and systems.
• Apply AI-powered engineering and agentic tooling deeply across the software development lifecycle, accelerating discovery, codebase understanding, requirements, development, testing, modernisation and delivery.
• Engineer for production from day one, embedding secure-by-design practices, resilience, performance engineering, observability, automated delivery and operational ownership throughout the lifecycle.
• Demonstrate Principal Engineer-level technical leadership and hands-on credibility, mentoring engineers, influencing architecture across teams, constructively challenging decisions and continually raising engineering standards.

Tech skills 

We don't expect you to know everything, but experience in several of the following will set you up for success:

• Front-End Engineering: React, Next.js, TypeScript
• Back-End Engineering: Java, Spring Boot, Spring Framework, microservices, RESTful APIs, Web APIs
• Architecture & Solution Design: Enterprise system design, scalable architecture patterns, distributed systems
• Event-Driven Architecture: Apache Kafka, event streaming, asynchronous architectures, real-time data processing
• Databases & Data Engineering: Oracle PL/SQL, MongoDB, AWS NoSQL services, high-availability and performance-optimised data layers
• Cloud Engineering: AWS, cloud-native services, scalable and secure cloud infrastructure
• Infrastructure as Code (IaC): AWS CDK, Terraform, AWS CloudFormation
• DevSecOps & CI/CD: GitHub Actions, CI/CD pipelines, security automation, continuous delivery
• Quality Engineering & Test Automation: Unit testing, component testing, integration testing, end-to-end testing, Specmatic API contract testing
• Source Code & Repository Strategy: GitHub, advanced Git workflows, branching strategies, monorepo architecture, TurboRepo
• AI-Assisted & Agentic Development: Generative AI, agentic software development, Roo Code, Cline, Claude Code, GitHub Copilot
• Observability & Site Reliability Engineering: Observe, Prometheus, Grafana, PagerDuty, monitoring, alerting, operational reliability