Senior Backend Developer

3ap

. Own backend work end-to-end .

Posted 10/26/2026full-timeBelgrade • SerbiaSeniorWebsite

Core Competencies

Role fit

Core Competencies

Use this summary to align your resume positioning with the role.

Demonstrates expertise in building and shipping production-ready backend systems using Java and Spring, with a strong focus on REST API design, microservices architecture, and rigorous testing of AI outputs. Proficient in utilizing AI tools and frameworks while effectively communicating technical concepts to non-technical stakeholders.

Highest-signal resume keywords

Java Backend DevelopmentSpring FrameworkREST API DesignMicroservices ArchitectureDocker and Kubernetes

ATS Keywords

Tailor your resume

Applicant Tracking System Keywords

Tip: use these terms in your resume and cover letter to boost ATS matches.

Hard Skills

JavaSpringREST APIMicroservicesDockerKubernetesJenkinsOpenShiftAI ToolsTesting and Validation

Soft Skills

Exceptional CommunicationCollaborative Problem SolvingKnowledge Sharing

Tools & Technologies

GitHub CopilotClaudeAI Tools

Certifications & Qualifications

University Degree in Computer Science

Industry Keywords

Production-Ready ApplicationsUnstructured DataNon-Deterministic AI OutputsGuardrails Around AI Output

Tech Stack

Tools & technologies

DockerJavaJenkinsKubernetesMicroservicesOpenShiftSpring

About the role

Key responsibilities & impact

Own backend work end-to-end
Build backend systems with Java and Spring
Ship production-ready applications integrating LLMs and unstructured data
Design and integrate REST APIs
Work with microservices architecture
Use Docker, Kubernetes, Jenkins, and OpenShift
Test and validate systems, particularly non-deterministic AI outputs
Collaborate with designers, frontend engineers, product managers, and stakeholders
Present work to non-technical people
Use AI tools such as GitHub Copilot or Claude in production workflows
Build guardrails around AI-generated output
Identify flaws in logic before production
Learn and adopt new AI tools and frameworks
Solve difficult problems collaboratively and share knowledge across project teams

Requirements

What you’ll need

5+ years of experience building backend systems with Java (Spring) and its ecosystem
Track record of shipping production-ready applications, including applications integrating LLMs and unstructured data
Strong REST API design and integration experience
Solid understanding of microservices architecture
Hands-on experience with Docker, Kubernetes, Jenkins, and OpenShift
Rigorous testing and validation, especially for non-deterministic AI outputs
University degree in CS or equivalent
Fluent English
Experience with GitHub Copilot, Claude, or similar AI tools in an actual workflow
Ability to build guardrails around AI-generated output
Ability to learn new tools quickly
Exceptional communication skills and ability to present work to non-technical people

Benefits

Comp & perks

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
Employee referral program
People-first culture
Flat structure
No bureaucracy
Work using current technology, including AI in production