Senior Fullstack Engineer (H/U/M/A/N) full-time (remote/hybrid)

Job description

freshcells systems engineering GmbH is a software service provider based in Düsseldorf with a dynamic team of over 60 creative experts from various fields. We focus on authenticity, individual talent development and open communication . We build on respect, trust and responsibility . As an innovation-driven company , we invest in new ideas . We know that the best results are achieved as a team . We make mistakes , but we learn from them . We are open and courageous for new ways . Join us on our exciting journey in what is probably the most important and forward-looking area - software development - as a Senior Fullstack Engineer (m/f/d) in full-time hybrid or remote. We hire people who want to understand how things work, not just how to wire them together. You don’t have to know everything. But you should want to know why . We’re seeking a person who thinks like an engineer: Sees code as part of a system, not just a task Cares deeply about clarity, naming, and tradeoffs Wants to understand why something works, not just that it does Feels uneasy when the wrong abstraction appears repeatedly Can clearly explain concepts to a junior dev, PM, or their future self We don’t expect trivia—but we do expect curiosity and solid mental models. You should be familiar with: Why { } === { } is false in JavaScript What happens if you pass a new object in a React hook dependency array How closures work and why they matter Avoiding side effects that break memoization Why abstraction is about boundaries—not just DRY If you already care about reference semantics, testability, or naming, you’ll feel at home here. Tasks Develop and maintain backend APIs using Node.js/TypeScript Implement complex frontend behaviors with React Work across a shared, client-customizable codebase Recognize emerging patterns, craft reusable abstractions, and refactor responsibly Influence structure, testing, and performance in the codebase Contribute to technical decision-making—not just execute tickets Requirements Very good knowledge of Node.JS Strong knowledge of ES 6 JavaScript as well as extensive knowledge of frameworks and libraries such as reactJS, vue.js and/or Angular Sound experience with relational or non-relational databases Good knowledge of data structure design Competences in consuming and creating web services based on ReST and especially GraphQL Know-how in performance optimization…