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Join FlixBus's B2B Sales & Distribution team as a Senior Kotlin Backend Engineer, where you'll design and develop backend services powering Flix's partner-facing ecosystem. This role involves building and maintaining REST APIs used by internal and external partners, participating in architectural decisions, and supporting significant modernization of backend architecture.
Key responsibilities include designing backend services in Kotlin and Spring Boot, building and maintaining REST APIs for partners, participating in architectural decisions and technical modernization initiatives, improving observability and performance using DataDog, and contributing to CI/CD pipelines and cloud infrastructure on AWS and Kubernetes. You'll work in an AI-native development environment featuring AI-integrated code review automation and an internal Claude Code plugin marketplace covering Kotlin/Spring Boot conventions, architectural patterns, testing practices, database guidelines, and team-specific conventions.
Required qualifications: 5+ years of professional backend development experience with JVM languages, with at least 2 years of commercial Kotlin experience. You need hands-on Spring Boot expertise, experience building and maintaining REST APIs and distributed systems, solid SQL knowledge and relational database design (MySQL and PostgreSQL), sound software engineering fundamentals and clean code practices, and familiarity with ORM and persistence layers. You should be collaborative and pragmatic, comfortable working in cross-functional Agile teams.
Preferred experience includes AWS, Kubernetes, GitLab CI/CD, Kafka, Terraform, LLM integrations, RAG systems, AI product development, or legacy system migration. The role offers a tech-driven environment with competitive pay, strong growth opportunities, and a culture of collaboration and ownership.
