Junior Full-Stack Developer Next.js

Since being taken over by CHAPTERS Group AG in 2025, Linear Service GmbH has been building a completely new cloud product alongside its established core system for association management and accounting. The existing system remains – it continues to run and is used daily by our customers from clubs, associations, and schools. In parallel, a modern cloud product line is being created from scratch, conceived from the outset with agent-based AI features (chatbot, copilot, MCP). Behind this lie 35 years of experience and a loyal customer base – ahead of us lies an agent-based future that we are now shaping.

For this new product, we are looking for a Junior Developer (m/f/d) who doesn't come with years of experience, but with the right attitude: You develop AI-first from the beginning – coding agents are not a tool for you, but your standard workflow – and you want to learn how to not only use agents but also build and orchestrate them yourself.

You will work closely with our CTO and grow step-by-step into the entire platform, from the frontend through APIs to the database. You don't need to master the Next.js ecosystem blindly yet – you need to want to learn it.

Responsibilities

• Feature Development: Implementation of clearly defined features in our new Next.js cloud platform (React, TypeScript, PostgreSQL) – with mentoring, growing responsibility, and code reviews by the CTO.
• AI-First Development: You work daily with coding agents (Claude Code, Cursor, GitHub Copilot or similar), master the planning, delegation, and review of agent-generated code, and help us further improve our AI development workflows.
• Agent Orchestration: Contribution to our AI features – tool integrations via MCP, agent flows with LangGraph, prompt design, evals, and guardrails for chatbot and copilot.
• Frontend: Building modern, responsive user interfaces with React/Next.js.
• Backend Fundamentals: Implementing API endpoints and database queries, thereby building full-stack competence step-by-step.
• Quality & Documentation: Writing tests, documenting features – in a way that AI agents can also work with them.

Qualifications

• Tech Stack: Solid foundation in JavaScript/TypeScript and initial practical experience with React and Next.js – from internships, working student jobs, bootcamps, or personal projects. SQL and git are mastered.
• AI-First Mindset (Mandatory): You already program with AI-powered tools (Cursor, Claude Code, Copilot, etc.) and can show what you have built with them.
• Willingness for Agent Orchestration (Mandatory): You want to understand how LLM agents work – tool calling, MCP, LangGraph/LangChain, prompting, evaluation – and ideally have already built your own small agents, chatbots, or MCP servers.
• Background: Completed degree (Computer Science or similar), apprenticeship as IT specialist – or career changers with a demonstrable portfolio.
• Learning Curve: High self-initiative, quick learning, joy in learning from reviews and mistakes.
• Language & Legal: Fluent German language skills and a valid work permit for Germany.
• Nice-to-have: PostgreSQL, Next.js App Router, experience with LangGraph/LangChain in a personal project, open-source contributions, basic knowledge of accounting or association work.

Benefits

• Mentoring: Direct collaboration with the CTO, regular code reviews, steep learning curve.
• Creative Freedom: Full freedom in choosing your development setup and your preferred coding agents.
• True Green Field: No legacy issues – you will build a new cloud product from the start.
• 100% Flexibility: Fully remote capable, flexible working hours; office in Berlin Mitte if you wish.
• Mobility: Deutschlandticket will be covered.
• Development: Further training and exchange with over 60 other software companies in the CHAPTERS Group.
• Sports & Health: Subsidized membership through Urban Sports Club.

Unleash your potential as a Junior Full-Stack Developer (Next.js) at Linear Service GmbH! Shape software that helps associations achieve more. Become part of our 35-year success story!

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