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