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

freshcells systems engineering GmbH; Düsseldorf; Hybrid; EUR 75,000 - 110,000; Full time

Job summary

freshcells systems engineering GmbH in Düsseldorf seeks a Senior Fullstack Engineer (m/f/d) for a full-time hybrid or remote role. Build backend APIs with Node.js/TypeScript and craft engaging frontend with React.

You’ll work on a shared, client-customizable codebase, pursue clean architecture, and influence testing, performance, and overall code quality. Fluent English is required; German language skills are a plus.

Qualifications

• Very good knowledge of Node.js and TypeScript.
• Strong knowledge of ES6 JavaScript and frameworks such as React, Vue.js or Angular.
• Relational or non-relational databases experience.
• Data structure design knowledge.
• Experience consuming/creating REST and GraphQL services.
• Performance optimization know-how.
• Basic knowledge of HTML/CSS is helpful.
• Experience with agile development and automated testing.
• Basic API security knowledge.
• Fluent in English.

Responsibilities

• 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.

Skills

Node.js

ES6 JavaScript

English (Fluent)

Tools

React

Vue.js

Angular

TypeScript

REST

GraphQL

HTML/CSS basics

SQL/NoSQL databases

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
• 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.

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!