Senior Fullstack Java Developer (M/F) - Freelance

On behalf of one of Luxembourg's leading insurance groups, GS Advisory is looking for several Fullstack Java Developers to join a multidisciplinary Agile team on a long-term mission. You will work on a business-critical application portfolio within the local contracts domain, in an environment where code quality, autonomy and knowledge sharing genuinely matter.

This is a role for developers who enjoy taking ownership of a mature system: understanding its history, mastering its business rules, and modernising it step by step rather than rewriting it from scratch.

The mission :

- Design, develop, test, deploy and monitor applications, primarily in Java 8.

- Maintain and evolve REST APIs written in Scala and existing frontend interfaces, and contribute to the progressive modernisation of a legacy application portfolio.

- Take an active part in Agile ceremonies and practices (Kanban and Scrum) within a multidisciplinary team.

- Write and maintain automated tests (Playwright), and use AI-assisted development tools daily to improve quality, maintainability and productivity.

- Build deep functional and technical expertise on a strategic business domain, and support your colleagues through pair programming, code reviews and knowledge sharing.