Senior Full Stack Developer – Java, React

Jobtailor; Köln; Vor Ort; EUR 90.000 - 120.000; Vollzeit

Zusammenfassung

Jobtailor in Köln is seeking a senior software engineer who will deliver features across the full stack using React/TypeScript frontend and Java/Spring Boot backend, including GraphQL and REST layers.

You will work with AI agents to accelerate scaffolding, refactor to reduce technical debt, and contribute to a multi-module Spring Modulith architecture while mentoring peers and reviewing code.

Qualifikationen

• 5+ years of professional software development experience shipping and owning features end-to-end within a production SaaS product.
• Extreme comfort with experimenting with agentic workflows and AI tools to accelerate scaffolding, refactoring, and debugging.
• Deep proficiency in Java 17+ and Spring Boot ecosystem, plus PostgreSQL and REST/GraphQL API design.
• Strong frontend engineering skills with React 18, TypeScript, Redux, and Apollo Client.
• Fluent in testing across the full stack and Git-based workflows in GitLab CI/CD.
• Business fluency in English and a curiosity to adapt to new tools and architectures.

Aufgaben

• Deliver features across the full stack using React/TypeScript frontend and Java/Spring Boot backend, including GraphQL and REST layers.
• Work by default in an AI-augmented way, using modern AI coding agents and tools to increase output.
• Implement robust services with Spring Boot, manage data with PostgreSQL and Flyway migrations, optimize Elasticsearch queries.
• Build responsive React components and manage global state with Redux, fetching data with Apollo Client and visualizations with D3/Recharts.
• Maintain testing standards with JUnit, Mockito, Testcontainers, WireMock and frontend testing with Jest, Cypress, Playwright.
• Refactor complex features into modular code, reduce technical debt, and contribute to a multi-module Spring Modulith architecture.
• Review merge requests and mentor engineers, serving as an autonomous technical reference point.

Kenntnisse

End-to-end feature ownership

English fluency

Mentoring

Code review

Tools

Java 17+

Spring Boot

React 18

TypeScript

Redux

Apollo Client

GraphQL

REST API design

PostgreSQL

Elasticsearch

Apache Jena

JUnit

Mockito

Testcontainers

WireMock

Jest

Cypress

Playwright

GitLab CI/CD

D3

Recharts

Jobbeschreibung

Responsibilities

• 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.
• 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.
• 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.
• 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.
• 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.
• Help carve complex features into clean modules, reduce technical debt, and actively contribute to our ongoing evolution toward a multi-module Spring Modulith architecture.
• Serve as an autonomous technical reference point within the team by reviewing merge requests, sharing domain knowledge, and mentoring less experienced engineers.

Requirements

• 5+ years of professional software development experience shipping and owning features end-to-end within a production SaaS product.
• Extreme comfort and enthusiasm for experimenting with next-generation agentic workflows, using tools like Cursor and Claude Code to accelerate scaffolding, refactoring, and debugging.
• 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.
• Strong frontend engineering skills utilizing React 18, TypeScript, Redux state management, and Apollo Client.
• Complete fluency in testing across the full stack and managing Git-based workflows within a GitLab CI/CD environment.
• Business fluency in English, an exceptional solution-oriented mindset, and a genuine curiosity to adapt quickly to new domain-heavy tools and architectures.