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

<p><strong>freshcells systems engineering GmbH is a software service provider based in Düsseldorf with a dynamic team of over 60 creative experts from various fields.</strong></p><p>We focus on <strong>authenticity, individual talent development</strong> and <strong>open communication</strong>. We build on <strong>respect, trust</strong> and <strong>responsibility</strong>. As an <strong>innovation-driven company</strong>, we invest in <strong>new ideas</strong>. We know that the <strong>best results</strong> are <strong>achieved as a team</strong>. We make <strong>mistakes</strong>, but we <strong>learn from them</strong>. We are <strong>open</strong> and courageous for <strong>new ways</strong>.</p><p>Join us on our exciting journey in what is probably the most important and forward-looking area - software development - as a <strong>Senior Fullstack Engineer (m/f/d)</strong> in full-time hybrid or remote.</p><p>We hire people who want to understand how things work, not just how to wire them together.</p><p>You don’t have to know everything. But you should want to know <em>why</em>.</p><p>We’re seeking a person who thinks like an engineer:</p><ul><li><p>Sees code as part of a system, not just a task</p></li><li><p>Cares deeply about clarity, naming, and tradeoffs</p></li><li><p>Wants to understand why something works, not just that it does</p></li><li><p>Feels uneasy when the wrong abstraction appears repeatedly</p></li><li><p>Can clearly explain concepts to a junior dev, PM, or their future self</p></li></ul><p>We don’t expect trivia—but we do expect curiosity and solid mental models. You should be familiar with:</p><ul><li><p>Why { } === { } is false in JavaScript</p></li><li><p>What happens if you pass a new object in a React hook dependency array</p></li><li><p>How closures work and why they matter</p></li><li><p>Avoiding side effects that break memoization</p></li><li><p>Why abstraction is about boundaries—not just DRY</p></li></ul><p>If you already care about reference semantics, testability, or naming, you’ll feel at home here.</p><h2>Tasks</h2><ul><li><p>Develop and maintain backend APIs using Node.js/TypeScript</p></li><li><p>Implement complex frontend behaviors with React</p></li><li><p>Work across a shared, client-customizable codebase</p></li><li><p>Recognize emerging patterns, craft reusable abstractions, and refactor responsibly</p></li><li><p>Influence structure, testing, and performance in the codebase</p></li><li><p>Contribute to technical decision-making—not just execute tickets</p></li></ul><h2>Requirements</h2><ul><li><p>Very good knowledge of Node.JS</p></li><li><p>Strong knowledge of ES 6 JavaScript as well as extensive knowledge of frameworks and libraries such as reactJS, vue.js and/or Angular</p></li><li><p>Sound experience with relational or non-relational databases</p></li><li><p>Good knowledge of data structure design</p></li><li><p>Competences in consuming and creating web services based on ReST and especially GraphQL</p></li><li><p>Know-how in performance optimization</p></li><li><p>Basic knowledge of HTML and CSS is helpful</p&