Senior Staff Java Engineer

We are seeking an experienced and opinionated Java Developer to join our high-performing engineering team, building low-latency, high-throughput systems in the payments processing domain. This hybrid role (UK) involves designing scalable, real-time services using modern technologies. If you’re passionate about performance, Core Java, and elegant engineering practices, we’d like to hear from you. Key Responsibilities - Design and develop low-latency, high-throughput backend systems using Core Java and Spring Boot - Build and maintain RESTful APIs and microservices powering secure payment workflows - Work with XML-based messaging standards used in financial transactions - Deploy, monitor, and scale applications on Red Hat OpenShift and AWS - Integrate and optimize solutions using MongoDB and other NoSQL/SQL datastores - Collaborate closely with DevOps, Product, and QA teams - Participate in architectural discussions and mentor engineers - Lead performance tuning, fault tolerance, and observability improvements Required Skills & Experience - 7+ years Core Java development with strong performance/memory optimization - Expertise in Spring Boot and microservices - Proven experience building low-latency, high-throughput systems - Hands-on experience with XML, message parsing, and transformation - Deployment experience on OpenShift and/or Kubernetes - Strong AWS knowledge (ECS, EKS, Lambda, S3, etc.) - Solid understanding of MongoDB / NoSQL patterns - Experience in payments, financial services, or banking systems - Strong communication skills and comfort in an opinionated, engineering-driven environment Nice to Have - Experience with Kafka, RabbitMQ, or similar messaging platforms - Exposure to container security and performance tuning on OpenShift - Knowledge of payment gateways, ISO 20022, SWIFT, or related standards Location & Work Environment - Hybrid: London (UK) - Fast-paced, collaborative, engineering-led culture - Strong focus on autonomy, architectural decision-making, and clean code