Senior Backend Developer

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 of experience building backend systems with Java (Spring) and its ecosystem

• Track record of shipping production-ready applications, including ones that integrate LLMs and unstructured data

• Strong REST API design and integration experience, and solid understanding of microservices architecture

• Hands-on with Docker, Kubernetes, Jenkins, and OpenShift

• Rigorous about testing and validation, especially where AI outputs are non-deterministic

• You think about the full product, not just your layer. A bad integration can sink a good solution

• You’re an exceptional communicator, comfortable talking to designers, frontend engineers, product managers, and stakeholders, and presenting your work to non-technical people

• You’ve gone deep into AI tools, not just used them casually, and know how to get real production value out of them, while treating AI output as a draft, not a deliverable

• You’ve used GitHub Copilot, Claude, or similar in your actual workflow, and you build guardrails around what they produce

• 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

• University degree in CS or equivalent

• Fluent English

Useful, but not required:

• Node.js, TypeScript, PostgreSQL, or MongoDB

• Frontend experience with React, Angular, or Vue

• CI/CD and DevOps hands-on experience

• Familiarity with API tools like Postman or Insomnia

• 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 60+ 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