Senior Java Software Engineer

Senior Java Engineers — Build a New Platform from the Ground Up Location: London, United Kingdom — hybrid, 3 days per week in the office Employment type: Full-time Openings: Two The opportunity Join a leading Exchange in a newly established Sustainability & Physical Markets (SPM) engineering team at the beginning of a major transformation. Over the next three years, we’ll modernise a legacy .NET estate, migrate core capabilities to Java and break an established monolith into scalable microservices. You’ll have the opportunity to shape the architecture, influence technical decisions and take genuine ownership—without being constrained by a platform whose direction has already been decided. This is a hands-on AVP-level position within a small, focused team, ideal for an experienced engineer who enjoys solving complex modernisation challenges and building technology designed to last. Two roles, one ambitious roadmap We’re hiring for two positions under a shared job description: Full-stack Engineer: predominantly back-end Java, with some React.jsJava Engineer with DevOps responsibilitiesJava-first, with meaningful .NET exposure The role is approximately 70% Java and 30% .NET. Java is the future of the platform. You’ll build new microservices, REST APIs and data services using Spring Boot. The .NET work is equally important: you’ll understand, maintain and safely migrate existing C# systems as their capabilities move into the new Java architecture. We’re therefore looking for genuine working knowledge of .NET—not simply surface-level familiarity. The technology You’ll work across: Java and Spring BootMicroservices, REST APIs and data services.NET and C# legacy systemsKafka as the transport layerKubernetes and Helm on OpenShiftReact.js for the full-stack positionDevOps and platform engineering for the DevOps-focused positionPython for testing and automation—advantageous, but not essentialExperience with EKS or AKS is also relevant and transferable. What you’ll bring We’re looking for genuinely senior, hands-on engineers who can navigate both legacy complexity and modern architecture. You’ll ideally have: At least five years of professional engineering experienceStrong Java fundamentals and commercial Spring Boot experienceSolid working knowledge of .NET and C#Experience building microservices and APIsConfidence working across a mixed-technology estateThe judgement to migrate critical systems safely and incrementallyExperience with Kubernetes, containers or modern deployment platforms A capital-markets or financial-services background would be valuable, but it isn’t essential. Strong engineers from other complex, regulated or high-volume environments are encouraged to apply. We can teach the domain; engineering depth and sound technical judgement matter most. Why join? This is more than a maintenance role. You’ll help determine how a strategically important platform evolves—from its service boundaries and migration approach to the way it is built, deployed and operated. You’ll join early, work with a modern Java-led stack and see your decisions directly influence a significant three-year transformation. Important information The position requires three days per week in London officeVisa sponsorship is not available for either role