Senior Kotlin Developer - Freelance

Senior Kotlin Developer (PostgreSQL / TypeScript / AWS / JVM) – Remote

Day rate: £300 - £500
Duration: 9 months
Start Date: January 2026

My new client is looking for a Senior Developer with strong experience across Kotlin, TypeScript, PostgreSQL, API design and development, DevOps foundations, and cloud infrastructure. You will play a key role in building, growing, and maintaining both new and existing features within our platform—helping customers understand and reduce their carbon footprint.
Working closely with a high-performance engineering team, you will collaborate with colleagues to deliver high-quality solutions, contribute to platform stability, and have a continuous positive impact on the services we provide.

Key Responsibilities

• Design, develop, and maintain backend services and APIs using Kotlin and supporting technologies.
• Build new features and enhance existing functionality to meet project deliverables and ensure platform performance and stability.
• Develop well-structured, well-documented, and scalable API solutions aligned with industry best practices.
• Troubleshoot issues, build resilient systems, and promote visibility into platform health and observability.
• Work as a full-stack engineer with strong emphasis on backend components, ensuring backend services can support future frontend integrations.
• Collaborate with cross-functional stakeholders, communicating complex technical concepts in clear, non-technical terms.
• Contribute to continuous improvement, mentoring junior team members and coaching when needed.
• Ensure secure, high-performance, and scalable implementations across the platform.

Required Skills & Experience

• Strong Kotlin (or JVM) development experience — primary language for the platform.
• Experience with TypeScript and Node.js.
• Solid background in PostgreSQL and relational database design.
• Practical experience in API design and development, including documentation and best-practice architecture.
• Experience building resilient platforms, enabling monitoring, observability, and effective troubleshooting.
• Full-stack experience with strong backend focus, ideally with headless API-first architectures.
• Ability to understand complex technical issues, gather requirements from multiple stakeholders, and articulate challenges and solutions clearly.
• Understanding of cloud security and performance optimizations for scalable systems.

Nice to Have

• Passion for emerging technologies and API development trends, with the judgement to prioritise tools that bring real value.
• Experience with DevOps, especially:
  • Terraform & Terragrunt
  • Docker
  • AWS
  • Observability tools such as New Relic
• Exposure to:
  • Atlantis for Terraform PR automation
  • OpenTelemetry for observability
• Client-facing experience, with the ability to join occasional integration discussions with technical stakeholders.
• Strong communication and collaboration skills, including mentoring and supporting junior developers.
• Familiarity with a wide range of open-source tools and modern development practices.
• Practical experience delivering real-world software platforms.
• Experience with version control, CI/CD processes, and build pipelines.