Senior Backend Developer (Java, Spring, AI)

About the role

3ap is looking for a Senior Backend Developer in Belgrade who builds with intention in a fast-moving, AI-driven environment. Engineers own their work end-to-end, and teams run on separate projects but solve hard problems together and share what they learn.

Required profile

• 5+ years of experience building backend systems with Java (Spring) and its ecosystem
• Track record of shipping production-ready applications, including those integrating LLMs and unstructured data
• University degree in CS or equivalent; fluent English
• Exceptional communicator, able to talk to designers, frontend engineers, product managers and stakeholders and present to non-technical people
• Deep knowledge of AI tools, using them in production while treating AI output as a draft, and has used GitHub Copilot, Claude or similar in daily work
• Quick learner of new tools and open to working with Python

Required skills

• REST API design and integration, and microservices architecture
• Docker, Kubernetes, Jenkins and OpenShift
• Rigorous testing and validation, especially where AI outputs are non-deterministic
• Useful but not required: Node.js, TypeScript, PostgreSQL, MongoDB, React/Angular/Vue, CI/CD and DevOps, Postman or Insomnia, prompt engineering, insurance or finance background, German

What we offer

• A team of 60+ professionals in a flat, people-first culture with flexible hours and hybrid work
• 25 vacation days plus 2 extra 3ap holidays
• Private pension, private health insurance and 24/7 accident insurance
• Maternity and paternity leave support, team events and an employee referral program