Senior Backend Engineer (Java / Kotlin / AWS)
On-siteToruń, Kujawsko-Pomorskie, Poland
Job Summary
Design, build, and maintain JVM-based microservices using Java or Kotlin on AWS ECS, App Runner, and Lambda. Manage a rich data layer including PostgreSQL, DynamoDB, RedShift, and Redis while constructing event-driven integrations via RabbitMQ and SNS. Collaborate on API design across REST and BFF patterns, instrument services with OpenTelemetry and Prometheus, and ship via GitHub Actions CI/CD pipelines. Take full ownership of services from design through production, making architectural decisions and proactively identifying issues before incidents occur. Leverage AI-assisted development tools as part of your daily workflow.
Required Qualifications
- 5+ years of professional backend development in Java and/or Kotlin
- Fluent in Polish and English
- Solid understanding of distributed systems design, microservice patterns, and event-driven architecture
- Hands-on production experience with AWS (ECS, Lambda, S3, RDS or DynamoDB)
- Experience with relational databases (PostgreSQL) and NoSQL (DynamoDB or similar)
- Strong command of Docker and containerized deployments
- Experience with CI/CD pipelines – we use GitHub Actions
- Clean code as a practice, not a talking point – you write code that your colleagues can confidently extend
- Genuine ability to self-direct: you can take a loosely defined problem, break it down, make decisions, and deliver
Desired Qualifications
- Kotlin specifically (greenfield services are Kotlin-first)
- Experience with message brokers (RabbitMQ, SQS/SNS)
- Familiarity with observability tooling (OpenTelemetry, Prometheus/Grafana stacks)
- Background in logistics, routing, geospatial, or supply chain domains
- Experience integrating third-party APIs (auth providers, mapping/routing engines, analytics)
- Familiarity with AI-assisted development tools
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