Senior Software Engineer — Java / Microservices

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

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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.

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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

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Tech Stack

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

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Requirements

Must have:

• Strong experience with Java 21+ and Spring Boot MVC
• Hands-on knowledge of Kafka, PostgreSQL and/or MongoDB
• Familiarity with Hexagonal / Clean Architecture and microservices patterns
• Experience with automated testing (Spock or JUnit, Testcontainers, contract testing)
• Proficiency with Kubernetes, Helm, and GitLab CI pipelines
• Solid understanding of OAuth2/JWT-based security
• Mandatory proficiency with AI coding tools — Claude Code is the company standard; experience with agentic development workflows is a strong plus

Nice to have:

• Experience with Spring WebFlux (reactive stack)

• Familiarity with OpenFGA or similar fine-grained authorisation systems

• Background in Consumer-Driven Contract testing (Spring Cloud Contract)

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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