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 Open. Shift 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: Web. Flux / 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