Job description
Senior Java Software Engineer (Freelance)
Contract Overview
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Start date: End of January 2026
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End date: End of June 2026
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Contract type: Freelance / B2B
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Daily rate: up to €320/day
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Eligibility: EU residency required
Location & Work Model
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On-site: 2–3 days per month in Luxembourg (planned and agreed in advance)
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Remote: Remaining days worked remotely from within the EU
Role Summary
We are looking for a Senior Java Software Engineer to support a large-scale backend system within a public-sector IT environment. The role focuses on building and extending Java / Spring Boot services, with strong attention to software design, code quality, and test-driven development.
You will work on backend components that expose data via RESTful web services and process incoming events in an event-driven architecture.
Key Responsibilities
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Design and develop backend services using Java and Spring Boot
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Implement and maintain RESTful APIs
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Apply object-oriented design principles and appropriate design patterns
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Contribute to test-driven development and automated testing
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Develop clean, maintainable, and well-documented code
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Support build, deployment, and release processes
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Collaborate with other engineers in a structured, enterprise environment
Required Technical Skills
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Strong experience with Java backend development
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Proven hands-on experience with Spring Boot
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Solid understanding of object-oriented programming
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Experience with REST APIs
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Test automation / TDD (JUnit required; Cucumber is a plus)
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CI/CD experience using Jenkins
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Source control and release management with GitHub
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Familiarity with event-driven systems (Kafka or similar)
Nice to Have
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Experience working in large-scale or regulated environments
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Exposure to integration-heavy systems
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Experience with messaging or streaming platforms
