Company freshcells systems engineering GmbH is a software service provider based in Düsseldorf with a dynamic team of over 50 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, work as a team, learn from mistakes, and embrace new ways. About the Role We are looking for a Senior Fullstack Engineer (m/f/d) to join our team in full‑time hybrid or remote. The role is a hands‑on software developer who understands how things work, not just how to wire them together. What You'll Do Develop and maintain backend APIs using Website. Implement complex frontend behaviors with React. Work across a shared, client‑customisable codebase. Recognise emergent patterns, craft reusable abstractions, and refactor responsibly. Influence structure, testing and performance in the codebase. Contribute to technical decision‑making, not just execute tickets. What We Expect We are looking for a person who thinks like an engineer: Sees code as part of a system, not just a task. Cares deeply about clarity, naming and trade‑offs. 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. Additional knowledge required: Understand why { } === { } is false in JavaScript. Know what happens if you pass a new object in a React hook dependency array. Know how closures work and why they matter. Avoid side effects that break memoisation. Know that abstraction is about boundaries, not just DRY. Requirements Very good knowledge of Node.js. Strong knowledge of ES6 JavaScript and frameworks such as React, Vue.js, and/or Angular. Experience with relational or non‑relational databases. Good knowledge of data structure design. Competences in consuming and creating REST and GraphQL web services. Know‑how in performance optimisation. Basic knowledge of HTML and CSS is helpful. Experience with agile development and automated software testing. Basic knowledge in API security. Fluent in English. Nice to Have Experience with PHP frameworks such as Symfony, Laravel or Yii. Experience with containerisation technologies such as Docker. Experience with container orchestration (Kubernetes, OpenShift, Docker Swarm). Knowledge of designing twelve‑factor applications. Knowledge of continuous integration tools like Jenkins. Experience with Next.js and TypeScript. Diversity & Inclusion All people are welcome here, regardless of gender, age, sexual identity, origin, religion, ideology or disability. The main thing is that you fit in with us. Contact If you are interested in a wide‑ranging portfolio of projects, want to continuously develop yourself and enjoy working independently and responsibly, get in touch with us: recruiting((at))freshcells(.)de. We look forward to hearing from you! #J-18808-Ljbffr