Fullstack Developer | React, Next.js, TailwindCSS, Java & Spring Boot
Aktualisiert am 30.09.2025
Profil
Freiberufler / Selbstständiger
Remote-Arbeit
Verfügbar ab: 01.09.2025
Verfügbar zu: 10%
davon vor Ort: 100%
React
TypeScript
TailwindCSS
JavaScript
CSS3
HTML5
Jest
Playwright
Java 21
Spring Boot
JUnit
Node.js
GraphQL
REST
Bootstrap
Git
MongoDB
Azure
German
Native
English
Fluent
Russian
Fluent

Einsatzorte

Einsatzorte

Düsseldorf (+50km)
Deutschland
möglich

Projekte

Projekte

6 Monate
2025-06 - heute

Knauf Customer Authorization

Fullstack Developer Java Spring Boot TypeScript ...
Fullstack Developer

As a freelance Fullstack Developer at Knauf Digital GmbH, I contributed to the development and optimization of internal software solutions with a focus on backend systems.

  • Migration and redevelopment of REST endpoints in the backend (Spring Boot, Java) and frontend (React, TypeScript)

  • Performance optimization of slow database queries in PostgreSQL, with a focus on Spring Data JPA

  • Active participation in agile processes within a Scrum team (Daily Standups, Refinements, Reviews)

  • Supporting the team with cross-functional technical challenges

  • Close collaboration with frontend and backend developers to ensure stable and reliable interfaces

  • Emphasis on clean, maintainable code and continuous improvement of existing components

Java Spring Boot TypeScript React GitHub Azure Devops PostgreSQL Next.js
Knauf Digital GmbH
Munich
4 Monate
2024-12 - 2025-03

Customer Portal

Next.js React TypeScript ...
Further development of a customer portal to be used as a white-label solution for S-Direkt.
  • Customization of the color scheme 
  • Adjustments in the content management system (CMS) 
  • Expansion of test coverage 
  • Addition of AWS Lambda functions for a new user pool
Next.js React TypeScript Storybook Contentful Vitest Cypress Bitbucket AWS Docker Kubernetes Datadog
andsafe AG
Münster, Westfalen
5 Monate
2024-11 - 2025-03

Personal Website

Next.js React TypeScript ...
Self-developed web presence to showcase my services as a fullstack developer. Special focus on performance, digital accessibility, HTML emails for verifications, and multilingual support (German/English).
  • UI/UX conceptualization 
  • Responsive design 
  • Implementation of a form with email verification 
  • Content management via Contentful using GraphQL queries 
  • Database management via Supabase with PostgreSQL 
  • Unit testing for form validation 
  • End-to-end testing for accessibility compliance 
  • Web animations 
  • SEO optimization 
  • Analysis of anonymized user meTech Stacktrics
Next.js React TypeScript TailwindCSS Contentful GraphQL Supabase PostgreSQL Vitest Playwright GitHub Actions Vercel
4 Monate
2024-08 - 2024-11

Employee Center (Internal Web Application)

Fullstack Developer React TypeScript Bootstrap ...
Fullstack Developer
Independent refactoring and redesign of outdated components within an employee center.
  • Responsive design 
  • Upgrading the React version by two major releases 
  • Migration and update of design components 
  • Ensuring accessibility compliance 
  • Refactoring and deduplication of code
React TypeScript Bootstrap Vitest Java Spring Boot Microservices GitLab Microsoft Azure
Sparkassen Direktversicherung AG
Düsseldorf
1 Jahr
2023-09 - 2024-08

Customer Center

React TypeScript Bootstrap ...
Refactoring and further development of a customer center for contract management within a Scrum team.
  • Responsive design 
  • Upgrading the React version by two major releases 
  • Cross-platform app development with Capacitor 
  • Implementation of security-related app features (e.g., SSL pinning) 
  • Optimization of scheduled jobs 
  • Bug fixing and further development of Java microservices 
  • Expansion of test coverage 
  • Refactoring and deduplication of code
React TypeScript Bootstrap Vitest Cypress Capacitor Node.js OAuth 2.0 Java Spring Boot Microservices REST Java Message Queue (JMS) GitLab Azure Pipelines Azure Cosmos DB
Sparkassen Direktversicherung AG
2 Monate
2023-07 - 2023-08

nscale 9

Java Kotlin GitLab ...
Further development of an Enterprise Content Management (ECM) system within a Scrum team.
  • Bug fixing in a Java-based environment
  • Access rights management in Windows environments 
  • Improvement and optimization of existing solutions
Java Kotlin GitLab Docker
CEYONIQ Technology GmbH
2 Monate
2022-12 - 2023-01

Connector Tool (Internal Web Application)

Java Quarkus TypeScript ...
Independent development of a tool for the structured collection of connector data (Secunet & RISE) and associated card data in medical practices.
  • Login interface for connector authentication 
  • Structured capture of connector data 
  • Dashboard view including network information 
  • Ordering functionality for expiring cards (eHBA, SMC-B)
Java Quarkus TypeScript React MUI Jest REST SOAP
DGN Deutsches Gesundheitsnetz GmbH
7 Monate
2022-02 - 2022-08

GUSBox Cockpit (Internal Web Application)

Java Quarkus JUnit ...
Complete replacement of an existing PHP-based control center with a new React-based application, acting as lead developer.
  • Development of a Single Page Application (SPA) 
  • Display of network-relevant information of the hardware box 
  • Configuration of the box via forms 
  • Integration of SMS, fax, and appointment calendar functionality 
  • PDF editing with input fields and live preview
Java Quarkus JUnit TypeScript React MUI Jest REST SQLite
DGN Deutsches Gesundheitsnetz GmbH
9 Monate
2021-04 - 2021-12

GUSClient 4

Java Quarkus JUnit ...
Independent development of the fourth generation of a medical communication client to complement existing practice management systems (PVS).
  • Design and development of RESTful APIs 
  • Implementation of a new graphical user interface (GUI) 
  • Adaptation to the corporate design 
  • Implementation of encrypted message sending 
  • CLI functionalities for pre-filling and pre-uploading data
Java Quarkus JUnit React MUI Jest REST SQLite picocli
DGN Deutsches Gesundheitsnetz GmbH
4 Monate
2020-12 - 2021-03

LOEM (Labor Order Entry Modul)

Java Swing JUnit ...
Independent refactoring of the entire Java codebase b(80k+ lines).
  • Deduplication of code 
  • Introduction of inheritance using abstract classes and interfaces 
  • Cleanup and correction of over 1,000 SonarLint issues 
  • Unit testing of the codebase with JUnit
Java Swing JUnit SonarLint
DGN Deutsches Gesundheitsnetz GmbH

Aus- und Weiterbildung

Aus- und Weiterbildung

3 Jahre
2017-10 - 2020-09

Computer Science

Bachelor of Science, Final Grade: 2.0, Heinrich Heine University Düsseldorf
Bachelor of Science, Final Grade: 2.0
Heinrich Heine University Düsseldorf

Position

Position


Kompetenzen

Kompetenzen

Top-Skills

React TypeScript TailwindCSS JavaScript CSS3 HTML5 Jest Playwright Java 21 Spring Boot JUnit Node.js GraphQL REST Bootstrap Git MongoDB Azure

Schwerpunkte

Responsives Design
Experte
Web-Entwicklung
Experte
Web-Design-Umsetzung
Experte
Web-Barrierefreiheit
Fortgeschritten

Produkte / Standards / Erfahrungen / Methoden

Skills

Frameworks

  • React
  • Next.js
  • Spring Boot
  • Quarkus
  • Node.js


Web Development

  • Responsive Design
  • UI/UX Optimization
  • Accessibility


UI Frameworks & Styling

  • TailwindCSS
  • Material UI
  • CSS/SCSS


API Development

  • REST with OpenAPI
  • GraphQL (Node.js)


Cloud Technologies

  • Microsoft Azure
  • Azure Service Fabric
  • Azure Cosmos DB


CI/CD & DevOps

  • Git
  • GitHub Actions
  • Datadog
  • Jenkins
  • Docker
  • SonarQube


Testing Methods

  • TDD, Unit and Integration Testing
  • Jest
  • JUnit5
  • Playwright


Agile Methods

  • Scrum
  • Kanban
  • Clean Code


Development Environment

  • IntelliJ IDEA (macOS, personal hardware)


Work Experience

04/2025 - today

Role: Self-Employed, Freelance Software Developer


Tasks:

  • Web Development
  • MVP Development
  • Technical Consulting
  • Software Development
  • Support & Maintenance


09/2023 - 03/2025

Role: Agile Software Developer

Customer: Sparkassen Direkt Versicherung AG 


Tasks:

  • Responsive Web Design
  • Refactoring and modernization of React applications, both technical and UX-focused
  • Cross-platform app development with Capacitor
  • Optimization of scheduled jobs
  • Bug fixing and further development of Java microservices
  • Accessible web development (up to Level AA compliance)


07/2023 - 08/2023

Role: Fullstack Developer

Customer: Ceyoniq Technology GmbH 


Tasks:

  • Bug fixing within a Java-based ECM system
  • Improvement and optimization of existing solutions
  • Thorough analysis and quick adaptation to new tasks


12/2020 - 06/2023

Role: Fullstack Software Developer

Customer: DGN Deutsches Gesundheitsnetz Service GmbH


Tasks:

  • Refactoring of existing Java applications
  • Design and development of RESTful APIs in Java
  • Development of several web applications using Java and React
  • Visual redesigns of existing web applications in React
  • Development of CLI applications in Java
  • Training colleagues in React
  • Participation in job interviews as a co-decision maker


02/2020 - 03/2020

Role: Intern in an Agile Scrum Team

Customer: sipgate GmbH


Tasks:

  • Refactoring of existing web applications in ReactJS 
  • Test-Driven Development (TDD) in JavaScript/TypeScript 
  • Development of a Node.js library in TypeScript 
  • Designing test cases with TestCafé 
  • Development of a Single Page Application using Spring MVC


Skills:

ReactJS, JavaScript, TypeScript, Node.js library, Spring MVC

Betriebssysteme

macOS
Experte

Programmiersprachen

JavaScript
ES6+
Java
Experte
TypeScript
Kotlin

Datenbanken

MongoDB
Experte
PostgreSQL
Fortgeschritten
Redis
Hibernate

Branchen

Branchen


Einsatzorte

Einsatzorte

Düsseldorf (+50km)
Deutschland
möglich

Projekte

Projekte

6 Monate
2025-06 - heute

Knauf Customer Authorization

Fullstack Developer Java Spring Boot TypeScript ...
Fullstack Developer

As a freelance Fullstack Developer at Knauf Digital GmbH, I contributed to the development and optimization of internal software solutions with a focus on backend systems.

  • Migration and redevelopment of REST endpoints in the backend (Spring Boot, Java) and frontend (React, TypeScript)

  • Performance optimization of slow database queries in PostgreSQL, with a focus on Spring Data JPA

  • Active participation in agile processes within a Scrum team (Daily Standups, Refinements, Reviews)

  • Supporting the team with cross-functional technical challenges

  • Close collaboration with frontend and backend developers to ensure stable and reliable interfaces

  • Emphasis on clean, maintainable code and continuous improvement of existing components

Java Spring Boot TypeScript React GitHub Azure Devops PostgreSQL Next.js
Knauf Digital GmbH
Munich
4 Monate
2024-12 - 2025-03

Customer Portal

Next.js React TypeScript ...
Further development of a customer portal to be used as a white-label solution for S-Direkt.
  • Customization of the color scheme 
  • Adjustments in the content management system (CMS) 
  • Expansion of test coverage 
  • Addition of AWS Lambda functions for a new user pool
Next.js React TypeScript Storybook Contentful Vitest Cypress Bitbucket AWS Docker Kubernetes Datadog
andsafe AG
Münster, Westfalen
5 Monate
2024-11 - 2025-03

Personal Website

Next.js React TypeScript ...
Self-developed web presence to showcase my services as a fullstack developer. Special focus on performance, digital accessibility, HTML emails for verifications, and multilingual support (German/English).
  • UI/UX conceptualization 
  • Responsive design 
  • Implementation of a form with email verification 
  • Content management via Contentful using GraphQL queries 
  • Database management via Supabase with PostgreSQL 
  • Unit testing for form validation 
  • End-to-end testing for accessibility compliance 
  • Web animations 
  • SEO optimization 
  • Analysis of anonymized user meTech Stacktrics
Next.js React TypeScript TailwindCSS Contentful GraphQL Supabase PostgreSQL Vitest Playwright GitHub Actions Vercel
4 Monate
2024-08 - 2024-11

Employee Center (Internal Web Application)

Fullstack Developer React TypeScript Bootstrap ...
Fullstack Developer
Independent refactoring and redesign of outdated components within an employee center.
  • Responsive design 
  • Upgrading the React version by two major releases 
  • Migration and update of design components 
  • Ensuring accessibility compliance 
  • Refactoring and deduplication of code
React TypeScript Bootstrap Vitest Java Spring Boot Microservices GitLab Microsoft Azure
Sparkassen Direktversicherung AG
Düsseldorf
1 Jahr
2023-09 - 2024-08

Customer Center

React TypeScript Bootstrap ...
Refactoring and further development of a customer center for contract management within a Scrum team.
  • Responsive design 
  • Upgrading the React version by two major releases 
  • Cross-platform app development with Capacitor 
  • Implementation of security-related app features (e.g., SSL pinning) 
  • Optimization of scheduled jobs 
  • Bug fixing and further development of Java microservices 
  • Expansion of test coverage 
  • Refactoring and deduplication of code
React TypeScript Bootstrap Vitest Cypress Capacitor Node.js OAuth 2.0 Java Spring Boot Microservices REST Java Message Queue (JMS) GitLab Azure Pipelines Azure Cosmos DB
Sparkassen Direktversicherung AG
2 Monate
2023-07 - 2023-08

nscale 9

Java Kotlin GitLab ...
Further development of an Enterprise Content Management (ECM) system within a Scrum team.
  • Bug fixing in a Java-based environment
  • Access rights management in Windows environments 
  • Improvement and optimization of existing solutions
Java Kotlin GitLab Docker
CEYONIQ Technology GmbH
2 Monate
2022-12 - 2023-01

Connector Tool (Internal Web Application)

Java Quarkus TypeScript ...
Independent development of a tool for the structured collection of connector data (Secunet & RISE) and associated card data in medical practices.
  • Login interface for connector authentication 
  • Structured capture of connector data 
  • Dashboard view including network information 
  • Ordering functionality for expiring cards (eHBA, SMC-B)
Java Quarkus TypeScript React MUI Jest REST SOAP
DGN Deutsches Gesundheitsnetz GmbH
7 Monate
2022-02 - 2022-08

GUSBox Cockpit (Internal Web Application)

Java Quarkus JUnit ...
Complete replacement of an existing PHP-based control center with a new React-based application, acting as lead developer.
  • Development of a Single Page Application (SPA) 
  • Display of network-relevant information of the hardware box 
  • Configuration of the box via forms 
  • Integration of SMS, fax, and appointment calendar functionality 
  • PDF editing with input fields and live preview
Java Quarkus JUnit TypeScript React MUI Jest REST SQLite
DGN Deutsches Gesundheitsnetz GmbH
9 Monate
2021-04 - 2021-12

GUSClient 4

Java Quarkus JUnit ...
Independent development of the fourth generation of a medical communication client to complement existing practice management systems (PVS).
  • Design and development of RESTful APIs 
  • Implementation of a new graphical user interface (GUI) 
  • Adaptation to the corporate design 
  • Implementation of encrypted message sending 
  • CLI functionalities for pre-filling and pre-uploading data
Java Quarkus JUnit React MUI Jest REST SQLite picocli
DGN Deutsches Gesundheitsnetz GmbH
4 Monate
2020-12 - 2021-03

LOEM (Labor Order Entry Modul)

Java Swing JUnit ...
Independent refactoring of the entire Java codebase b(80k+ lines).
  • Deduplication of code 
  • Introduction of inheritance using abstract classes and interfaces 
  • Cleanup and correction of over 1,000 SonarLint issues 
  • Unit testing of the codebase with JUnit
Java Swing JUnit SonarLint
DGN Deutsches Gesundheitsnetz GmbH

Aus- und Weiterbildung

Aus- und Weiterbildung

3 Jahre
2017-10 - 2020-09

Computer Science

Bachelor of Science, Final Grade: 2.0, Heinrich Heine University Düsseldorf
Bachelor of Science, Final Grade: 2.0
Heinrich Heine University Düsseldorf

Position

Position


Kompetenzen

Kompetenzen

Top-Skills

React TypeScript TailwindCSS JavaScript CSS3 HTML5 Jest Playwright Java 21 Spring Boot JUnit Node.js GraphQL REST Bootstrap Git MongoDB Azure

Schwerpunkte

Responsives Design
Experte
Web-Entwicklung
Experte
Web-Design-Umsetzung
Experte
Web-Barrierefreiheit
Fortgeschritten

Produkte / Standards / Erfahrungen / Methoden

Skills

Frameworks

  • React
  • Next.js
  • Spring Boot
  • Quarkus
  • Node.js


Web Development

  • Responsive Design
  • UI/UX Optimization
  • Accessibility


UI Frameworks & Styling

  • TailwindCSS
  • Material UI
  • CSS/SCSS


API Development

  • REST with OpenAPI
  • GraphQL (Node.js)


Cloud Technologies

  • Microsoft Azure
  • Azure Service Fabric
  • Azure Cosmos DB


CI/CD & DevOps

  • Git
  • GitHub Actions
  • Datadog
  • Jenkins
  • Docker
  • SonarQube


Testing Methods

  • TDD, Unit and Integration Testing
  • Jest
  • JUnit5
  • Playwright


Agile Methods

  • Scrum
  • Kanban
  • Clean Code


Development Environment

  • IntelliJ IDEA (macOS, personal hardware)


Work Experience

04/2025 - today

Role: Self-Employed, Freelance Software Developer


Tasks:

  • Web Development
  • MVP Development
  • Technical Consulting
  • Software Development
  • Support & Maintenance


09/2023 - 03/2025

Role: Agile Software Developer

Customer: Sparkassen Direkt Versicherung AG 


Tasks:

  • Responsive Web Design
  • Refactoring and modernization of React applications, both technical and UX-focused
  • Cross-platform app development with Capacitor
  • Optimization of scheduled jobs
  • Bug fixing and further development of Java microservices
  • Accessible web development (up to Level AA compliance)


07/2023 - 08/2023

Role: Fullstack Developer

Customer: Ceyoniq Technology GmbH 


Tasks:

  • Bug fixing within a Java-based ECM system
  • Improvement and optimization of existing solutions
  • Thorough analysis and quick adaptation to new tasks


12/2020 - 06/2023

Role: Fullstack Software Developer

Customer: DGN Deutsches Gesundheitsnetz Service GmbH


Tasks:

  • Refactoring of existing Java applications
  • Design and development of RESTful APIs in Java
  • Development of several web applications using Java and React
  • Visual redesigns of existing web applications in React
  • Development of CLI applications in Java
  • Training colleagues in React
  • Participation in job interviews as a co-decision maker


02/2020 - 03/2020

Role: Intern in an Agile Scrum Team

Customer: sipgate GmbH


Tasks:

  • Refactoring of existing web applications in ReactJS 
  • Test-Driven Development (TDD) in JavaScript/TypeScript 
  • Development of a Node.js library in TypeScript 
  • Designing test cases with TestCafé 
  • Development of a Single Page Application using Spring MVC


Skills:

ReactJS, JavaScript, TypeScript, Node.js library, Spring MVC

Betriebssysteme

macOS
Experte

Programmiersprachen

JavaScript
ES6+
Java
Experte
TypeScript
Kotlin

Datenbanken

MongoDB
Experte
PostgreSQL
Fortgeschritten
Redis
Hibernate

Branchen

Branchen

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