Job Title: Java Developer (Kotlin) Contract: 6 months (Inside IR35) - Extendable Location: Hybrid - West Sussex (2-3 days per week on-site) Rate: DOE Client: Leading Financial Services Organisation Overview We are working with a leading financial services client who is looking to engage an experienced Java Developer with strong Kotlin experience to join a high-performing engineering team. This is a critical contract role contributing to the design and delivery of scalable, high-quality backend systems within a complex enterprise environment. The successful contractor will be working on modernising platforms, building robust APIs, and contributing to solutions that operate at scale in a regulated environment. Key Responsibilities Design, develop, and maintain backend services using Java and Kotlin Build and enhance microservices-based architectures Develop clean, scalable, and well-tested code following best engineering practices Collaborate closely with product managers, architects, and other engineers Contribute to system design discussions and technical decision-making Ensure performance, security, and reliability of applications Work within Agile/Scrum delivery teams Required Skills & Experience 5 years of commercial software development experience Strong expertise in Java and hands-on Kotlin development Experience building backend services and APIs Solid understanding of microservices architectures Experience with Spring / Spring Boot Familiarity with CI/CD pipelines and modern development practices Strong problem-solving skills and ability to work in complex environments Desirable Experience Previous experience in financial services or regulated industries Cloud experience (AWS, Azure, or GCP) Experience with containerisation (Docker, Kubernetes) Knowledge of event-driven architectures (Kafka, messaging systems) Contract Details Initial 6-month contract, with strong likelihood of extension Inside IR35 Hybrid working : 2-3 days per week on-site Competitive day rate dependent on experience