Server-side Java Engineer- Financial Client Experience Required

Job Title: Server-side Java Engineer

Location: London (Hybrid – 3 days per week onsite)

Duration: 12Months+

Rate: 460GBP/Day Inside IR35 Max

Description

We're looking for a Server-side Engineer – Mobile Application Backend to join our team. In this role, you’ll design and develop the Backend-for-Frontend (BFF) API layer that powers mobile applications used by millions of users worldwide. You will work as part of the Mobile Engineering team—a multidisciplinary group of engineers, designers, and product experts—focused on building intuitive, high-performance backend services that deliver outstanding consumer experiences across digital touchpoints. The ideal candidate brings hands-on server-side engineering experience, strong problem-solving skills, and a passion for writing elegant and scalable code using modern technologies.

Responsibilities

• Design, develop, and maintain the mobile service layer (Backend-for-Frontend) supporting large-scale mobile applications
• Deliver secure, reliable, and high-performing server-side APIs for real-time consumer experiences
• Write clean, maintainable code and contribute to code reviews, refactoring, and continuous improvement initiatives
• Collaborate with mobile, product, and design teams to define solutions that enhance usability and functionality
• Troubleshoot and optimize application performance for responsiveness and scalability
• Create robust unit tests and integration tests to ensure software reliability
• Manage asynchronous processing, error handling, and performance optimization in distributed systems
• Support legacy system integrations and modernize existing codebases when required
• Follow CI/CD best practices and contribute to team development pipelines and build systems
• Actively share ideas, propose improvements, and participate in solution design discussions

Requirements (Must Have Skills)

• Proven experience building server-side applications with strong understanding of modern backend development practices
• Proficiency in Kotlin or related JVM languages (Java, Scala, etc.)
• Practical knowledge of RESTful and GraphQL (GQL) API design and integration
• Hands-on experience with Gradle or similar build tools
• Solid understanding of asynchronous programming, thread management, and performance optimization
• Experience working with CI/CD pipelines and automated testing frameworks
• Strong debugging and problem-solving skills with attention to system scalability and maintainability
• Bachelor’s degree in Computer Science or equivalent practical experience
• Ability to communicate effectively within cross-functional teams and adapt in fast-paced environments

Nice to Have Skills

• Experience designing or integrating RAML-based documentation into API workflows
• Familiarity with legacy system modernization or integration within enterprise environments
• Contributions to open-source projects or active involvement in developer communities
• Understanding of cloud-native development patterns or containerized deployment workflows (e.g., Docker, Kubernetes)
• Creativity and curiosity to explore innovative technical approaches for backend architecture improvements