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

Employment type
Full-Time

Work arrangement
No