Senior Java Engineer

Senior Software Engineer — Java / Microservices

Start date: ASAP Contract type: B2B (145-170pln) Work mode: 100% Remote

About the Team

You'll be joining a multidisciplinary team of senior engineers within a Consumer & Merchant domain, working on end-to-end parcel creation flows and some of the company's largest technical initiatives.

The team operates with high autonomy — engineers have real influence over architectural decisions and drive solutions from analysis all the way to production. The culture is built on knowledge sharing, mutual respect, and engineering excellence, with a genuinely friendly atmosphere.

Your Responsibilities

• Design and implement microservices following Hexagonal Architecture principles within a large-scale distributed system
• Drive topic analysis and requirement discovery — from business needs to solution architecture and delivery
• Build and maintain event-driven integrations using Kafka, Avro, and the Transactional Outbox pattern
• Write comprehensive automated tests: unit, integration, contract (Spock, Testcontainers, Spring Cloud Contract)
• Participate actively in code reviews and help raise the bar on code quality
• Work in a CI/CD environment: GitLab CI, Docker, Kubernetes + Helm (GitOps)
• Use AI-assisted development tools (Claude Code is the team standard) as a primary daily productivity tool — agentic, AI-first development is how this team operates

Language & Frameworks: Java 21, Spring Boot 3.x/4.x (MVC & WebFlux), Gradle Databases: PostgreSQL (JPA/Hibernate, R2DBC), MongoDB Messaging: Apache Kafka + Avro + Confluent Schema Registry Patterns: Hexagonal Architecture, Microservices, Event-Driven Design, Transactional Outbox Security: OAuth2 / JWT, Spring Security, OpenFGA Testing: Spock Framework, Testcontainers, WireMock, REST-Assured, Arch

Unit, PIT Mutation Testing Infrastructure: GitLab CI, Docker, Kubernetes + Helm (GitOps) Observability: Micrometer, Prometheus, SonarQube, Checkstyle AI Tooling: Claude Code (mandatory) / GitHub Copilot / Cursor

What Makes This Role Challenging

• Complex distributed system — dozens of microservices with numerous communication channels; understanding the big picture is as important as writing good code
• Near-100% uptime requirement — business-critical systems where reliability and fault tolerance are non-negotiable
• High autonomy from day one — independently analyse topics, identify stakeholders, and deliver solutions end-to-end
• AI-first way of working — using Claude Code and agentic workflows to accelerate delivery is a core part of how the team operates, not a nice-to-have