Senior Java Software Engineer

Job Title: Senior Java Engineer – High-Volume Payments PlatformLocation: New York, NY / New Jersey (Hybrid – 2-3 days per week onsite)Employment Type: Full-time, Permanent (W2)The OpportunityWe are looking for a Senior Java Engineer to join a small, elite team working on a high-impact payments platform for a top-tier investment bank. This is not a generic CRUD role. You'll be building and optimising systems that process millions of transactions per second – low-latency, high-throughput, mission-critical. The team is senior, empowered, and takes full ownership of services from design to production support. If you're a hands-on Java engineer who enjoys solving complex performance problems, debugging threading issues, and working with modern tech, this could be the right move for you.What You'll Be DoingDesign, build, and optimise low-latency, high-throughput microservices using Java 21, Spring Boot, Kafka, and KubernetesOwn services end-to-end – from architecture and implementation to deployment and production supportWork on concurrency, multithreading, and performance tuning – solving real production problemsCollaborate with a small, senior team – no hand-holding, real ownershipDrive code quality, engineering standards, and best practices across a wider organisationWhat We're Looking ForMust-Have:8+ years of hands-on Java development experienceStrong experience with multithreading and concurrency in productionExperience with Kafka (or similar messaging systems)Good understanding of distributed systems and cloud-native architecturesUS work authorisation (no visa sponsorship available)Nice to Have:Experience in banking, financial services, or paymentsExperience with Kubernetes and AWSKnowledge of FIX protocol or electronic trading systemsExperience with performance tuning and optimisationWhy Join?Meaningful Work: You'll be building systems that power global payments – your code will have real impactModern Tech Stack: Java 21, virtual threads, Kafka, Kubernetes, AWS – no legacy maintenanceSenior Team: Work alongside engineers with elite banking and tech backgroundsReal Ownership: You'll own services from design to production – not just ticketsLong-Term Stability: This is a permanent role – we've had people on this project for over 3 yearsHybrid Flexibility: 2-3 days per week onsite in NYC or NJ, rest remote