Senior Full Stack Developer | Java / React (f/m/d)

As a key member of our Product Development team, you will operate with a high degree of autonomy while collaborating closely with backend and frontend engineers, QA, DevOps, and product owners. In this role, you will directly align with cross-functional engineering stakeholders and indirectly impact our customers through the features and fixes you deliver, while having direct access to our CTO as a trusted mentor and technical sparring partner

How you’ll make an impact:

• End-to-End Feature Development: Deliver product features across the full stack, seamlessly moving between our React/TypeScript frontend and modern Java/Spring Boot backend, including the GraphQL and REST API layers in between. You take independent ownership of codebase areas from refinement to production.

• AI-Driven Velocity & Innovation: Work by default in an AI-augmented way, using modern AI coding agents and tools like Cursor and Claude Code to increase output and deliver features faster. You will push the limits of agentic workflows, mastering next-generation developer tools to keep our AI-native engineering team at the forefront of software innovation.

• Backend Engineering: Implement robust services utilizing Spring Boot, manage JPA/Hibernate against PostgreSQL with Flyway migrations, optimize Elasticsearch queries, and dive into semantic data structures using the Apache Jena RDF triplestore.

• Frontend Engineering: Build responsive React components and manage global state with Redux, fetching data with Apollo Client and implementing advanced data visualizations like D3 or Recharts optimized for large datasets.

• Quality Assurance & Testing: Uphold rigorous testing standards using JUnit, Mockito, Testcontainers, and WireMock on the backend, alongside Jest, Testing Library, Cypress, and Playwright on the frontend to maintain our SonarQube quality gate.

• Architecture & Modularization: Help carve complex features into clean modules, reduce technical debt, and actively contribute to our ongoing evolution toward a multi-module Spring Modulith architecture.

• Code Review & Mentoring: Serve as an autonomous technical reference point within the team by reviewing merge requests, sharing domain knowledge, and mentoring less experienced engineers.

What helps you succeed:

• Experience: 5+ years of professional software development experience shipping and owning features end-to-end within a production SaaS product.

• AI Tooling Curiosity: Extreme comfort and enthusiasm for experimenting with next-generation agentic workflows, using tools like Cursor and Claude Code to accelerate scaffolding, refactoring, and debugging. You view AI as an opportunity, not a threat.

• Backend Mastery: Deep proficiency in modern Java (17+) and the Spring Boot ecosystem (Spring Security, Spring Data JPA), alongside relational databases (PostgreSQL) and REST/GraphQL API design.

• Frontend Expertise: Strong frontend engineering skills utilizing React 18, TypeScript, Redux state management, and Apollo Client.

• Testing & Tools: Complete fluency in testing across the full stack and managing Git-based workflows within a GitLab CI/CD environment.

• Core Competencies: Business fluency in English, an exceptional solution-oriented mindset, and a genuine curiosity to adapt quickly to new domain-heavy tools and architectures.

• Nice-to-haves: It’s a major plus if you have experience with semantic web technologies (RDF, SPARQL, Apache Jena), Material UI (MUI 5), Elasticsearch, or a basic awareness of cloud/Kubernetes operations. Prior exposure to the life sciences or pharmaceutical domains (like FHIR or IDMP) is a bonus.

Why you’ll love working here:

• Hybrid work model: Work from our Cologne office with flexible hybrid arrangements.

• 30 days of paid vacation for a healthy work-life balance.

• Competitive salary package: A fixed salary package of €75,000 – €100,000 per year, aligned with your level experience and impact in this permanent, full-time role.