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

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

Basic knowledge of HTML and CSS is helpful

Experience with agile development in a team

Hands-on experience with automated software testing

Basic knowledge in API security

Fluent in English

Nice to have:
Experience of PHP, ideally with frameworks such as Symfony, Laravel or Yii

Experience with containerization technologies such as Docker etc.

Experience with container orchestration tools like, i.a., Kubernetes, OpenShift, or Docker Swarm

Knowledge of designing and adapting software to be twelve factor applications

Knowledge of continuous integration via tools like Jenkins

Experience with Next.js

Experience with TypeScript

All people are welcome here, regardless of gender, age, sexual identity, origin, religion, ideology, with or without a disability. The main thing is that you fit in with us.
If you are interested in a wide-ranging portfolio of projects, want to continuously develop yourself and enjoy working independently and responsibly, apply with the button on this page.
Want to get a glimpse of who we are and what it's like to work with us? Watch our video here: https://www.youtube.com/watch?v=9GEFoSIUPjU
We look forward to hearing from you!
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