Senior Backend Developer
TLDR
Design REST APIs with Java/Spring, testing AI outputs rigorously and adding guardrails before production.
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
Benefits
Flexible Work Hours
Flexible hours
Health Insurance
private health insurance
Private pension
Paid Parental Leave
Maternity and paternity leave support
Paid Time Off
25 vacation days + 2 extra 3ap holidays
Remote-Friendly
hybrid work
3AP AG is an agile software development company based in Switzerland, dedicated to enabling digital innovation and transformation for its clients. With a blend of strategy, design, and technology, they build scalable digital products and services while emphasizing continuous improvement and collaboration across disciplines.