Senior Backend Developer

Senior Backend Developer, Serbia We’re looking for a Senior Backend Developer who challenges assumptions, builds with intention, and thrives in a fast-moving, AI-driven environment. At 3ap, engineers own their work end-to-end. Our teams run on separate projects but solve hard problems together, share what they learn, and call out bad assumptions, including their own. What we need: - 5+ years with Java/Spring - Solid REST API design and integration experience - Hands-on with Docker, Kubernetes, Jenkins, and OpenShift - Rigorous about testing, especially where AI outputs are involved - Comfortable with API tools like Postman or Insomnia - You think about the full product, not just your layer. A bad integration can sink a good solution - You don’t stop at “it works.” You look for the flaw in the logic before someone else finds it in production - You pick up new tools fast. The AI landscape shifts week to week, and waiting to learn something familiar isn’t an option - You treat AI output as a draft, not a deliverable. You build guardrails, test rigorously, and verify manually - You’ve used GitHub Copilot, Claude, or similar in your actual workflow - You communicate clearly and don’t need much hand-holding to unblock yourself - University degree in CS or equivalent - Fluent English Useful, but not required: - WebFlux / reactive programming - Node.js, PostgreSQL, MongoDB, React, Angular, or Vue - CI/CD and DevOps hands-on experience - Prompt engineering or multi-step AI workflows - Comfort and openness to working with Python. Many modern AI tools and frameworks are built with Python at their core, so a willingness to learn and use it is important. - Background in insurance or finance - Any German What you get: - A team of 50+ professionals in a people-first culture, flat structure, and no bureaucracy - Work that uses current technology, including AI in production - Flexible hours, hybrid work - 25 vacation days + 2 extra 3ap holidays - Private pension, private health insurance, 24/7 accident insurance - Maternity and paternity leave support - Team events and an employee referral program