Senior Java Backend Developer

Quick Facts

Senior Java Backend Developer working on backend features, architecture, integrations, and automated testing. Emphasis on Java 21, Spring Boot, DDD/hexagonal architecture, and reliable async messaging (e.g., Artemis) with responsible use of AI coding tools.

Description

You will design and implement backend functionality with Java 21, set technical direction, and make architecture decisions to improve quality, stability, and scalability. The role includes domain-driven architecture, service integration in complex environments, SQL-based data modeling, and robust synchronous/asynchronous communication via messaging. You will also maintain code quality through automated tests and use AI tools to support coding and self code review, while critically validating AI outputs for correctness, security, and data protection.

Responsibilities

• Provide technical guidance and recommend best technology solutions
• Make decisions supporting system quality, stability, and scalability
• Design and implement new functionality in Java 21
• Develop domain architecture and integrate with other systems in complex environments
• Design asynchronous communication using events and commands for message-queue systems (e.g., Artemis)
• Ensure reliable service-to-service communication and integration consistency
• Model data and develop SQL-based solutions
• Maintain code quality with automated tests (e.g., JUnit, BDD, TestFX)
• Create and update technical documentation for modules, APIs, and integration processes
• Use AI tools (e.g., GitHub Copilot, Claude) for code generation/refactoring, problem analysis, test generation, and self code review
• Promote good practices for using AI tools with focus on code quality and security

Requirements

• Minimum 5 years of experience building commercial software in Java
• Very good knowledge of the Java ecosystem (JDK 21+) and Spring Boot
• Experience designing system architecture and making key technology decisions in complex environments
• Practical experience with design patterns, DDD, and hexagonal architecture
• Experience integrating systems and designing synchronous and asynchronous communication
• Ability to set technical direction and advocate engineering best practices
• Active Code Review participation with focus on quality, maintainability, and security
• Fluency with AI coding tools for development, analysis, and self code review
• Ability to critically verify AI-generated results and understand limitations (correctness, security, data protection)
• Experience with SQL, Maven, Docker, JUnit, and TestFX
• Understanding of performance, scalability, and security
• Polish and English at a level enabling smooth technical communication

Benefits

• B2B contract
• Access to offices in Poznań and Warsaw
• Preferential benefits (MultiSport, LuxMed private medical care, Uniqa group insurance, discounts on Maczfit and Samsung stores)
• Possibility to purchase or rent a passenger car on favorable terms
• Real impact on technologies used daily by millions; ideas are heard and innovation is encouraged
• Collaboration with specialists across different domains and opportunity to test innovative solutions