Kotlin Backend Engineer - (Freelance/Service Agreement)
We are looking for a skilled Kotlin Backend Engineer for service agreement collaboration. B2B Sales & Distribution team builds and operates the backend platform powering Flix's partner-facing ecosystem — including a self-management platform for partners, a back office portal for internal users, and an AI agentic bot supporting partner operations. The team is driving a significant modernization of its backend architecture and is working in an AI-native development environment.
Scope of services
Independent delivery of backend services in Kotlin and Spring Boot, including design, development, and maintenance
Building and maintaining REST APIs used by internal and external partners
Contributing to architectural decisions and technical modernization initiatives as a senior topic driver
Improving observability, performance, and reliability of backend systems using DataDog
Supporting CI/CD pipelines and cloud infrastructure on AWS and Kubernetes
Working within an AI-native development environment, including CI-integrated code review automation and an internal Claude Code plugin marketplace covering Kotlin/Spring Boot conventions, architectural patterns, testing practices, and database guidelines
Sharing Kotlin expertise and best practices with existing engineers on the Flix team who are transitioning from other languages, through code review, pairing, and technical guidance
Relevant expertise
4+ years of software engineering experience, primarily backend development with a JVM language, including some commercial experience with Kotlin
Hands-on Spring Boot experience
Experience building and maintaining REST APIs and distributed systems
Solid SQL knowledge and relational database design, including MySQL and PostgreSQL
Sound software engineering fundamentals and clean code practices
Clear written and spoken English communication skills
Preferred experience with: AWS, Kubernetes, GitLab CI/CD, Kafka, Terraform, LLM integrations, RAG systems, AI product development, or legacy system migration experience
Collaboration model
Cooperation based on a service agreement with independent delivery of agreed services and invoicing