> Markdown version of [/jobs/ext/3721252-java-kotlin-developer-hybrid-london-inside-ir35](https://www.wearedevelopers.com/jobs/ext/3721252-java-kotlin-developer-hybrid-london-inside-ir35). Every page supports `.md` or `Accept: text/markdown`. Links point to the HTML versions so they work for humans too. Agent guide: [/agents.md](https://www.wearedevelopers.com/agents.md).

---

# Java/Kotlin Developer | Hybrid, London | Inside IR35

- **Company:** Korn Ferry
- **Location:** London, UK
- **Salary:** £104,000.0
- **Contract:** Temporary contract
- **Skills:** RESTful API Modeling Language, Java (Programming Language), Application Programming Interfaces (APIs), Google App Engines, Application Performance Management, Unit Testing, Cloud Computing, Code Review, Continuous Integration, Software Debugging, Distributed Systems, Gradle, Mobile Application Software, Java Virtual Machine (JVM), Performance Tuning, Service Layer, Systems Integration, Reliability of Systems, Backend, Kotlin, Integration Tests, Kubernetes, Build Tools, Graphql, Front End Software Development, Asynchronous Programming, Api Design, Restful APIs, Code Restructuring, Docker
- **Published:** October 14, 2026
- **Apply:** https://www.careerboard.com/gb/en/find-jobs-in-United-Kingdom/-4DA52981BDAD387A26/

## About the Role

* Proven experience building Server Side applications with strong understanding of modern Back End 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

Nice to Have Skills

 * Experience designing or integrating RAML-based documentation into API workflows
 * Familiarity with Legacy system modernization or integration within enterprise environments
 * Understanding of cloud-native development patterns or containerized deployment workflows (eg, Docker, Kubernetes)

## Description

* 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