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Joseph Haas

Frontend Developer (Freelance)

Joseph Haas
Nicosia, Cyprus

Experience

Jul 2025 - Sep 2025
3 months
Berlin, Germany

Frontend Developer (Freelance)

diesdas digital GmbH

  • Developed Next.js applications with PayloadCMS & TypeScript
  • Built headless modules in Next.js for PayloadCMS
  • JavaScript
  • TypeScript
  • HTML5
  • CSS3
  • Node.js
  • Next.js
  • React
  • git
  • REST APIs
  • CSS Modules
  • Clean Code
  • Payload
Oct 2024 - Jun 2025
9 months
Cologne, Germany

Frontend Developer (Freelance)

Agentur Brandung GmbH

  • Enhanced a Next.js-based eCommerce application focusing on the checkout and account pages
  • Built headless Contentful modules in Next.js using GraphQL
  • Worked on an AI chatbot solution & an events page with complex theming requirements based on Next.js & TailwindCSS
  • Integrated the app with external APIs (Personio, Emarsys, etc.)
  • JavaScript
  • TypeScript
  • HTML5
  • CSS3
  • Node.js
  • Next.js
  • React
  • git
  • REST APIs
  • TailwindCSS
  • Clean Code
  • Contentful
  • GraphQL
Aug 2022 - Aug 2024
2 years 1 month
Fürstenwalde, Germany

Lead Software Developer (Freelance)

MCM Technology GmbH

  • Developed a React frontend, Express backend & multiple microservices in TypeScript
  • Set up, deployed & maintained the software on client servers using Ubuntu & Docker
  • Displayed measurement data in the frontend using d3 & recharts
  • Built MongoDB aggregation pipelines to process and transform measurement data
  • Architected & implemented complex requirements
  • Took on the role of lead developer and coordinated other developers
  • JavaScript
  • TypeScript
  • HTML5
  • CSS3
  • Node.js
  • React
  • React-Query
  • git
  • gitlab pipelines
  • docker
  • MongoDB
  • Ubuntu Server
  • Styled-Components
  • MUI
  • REST APIs
  • Express
  • MQTT
  • TailwindCSS
  • react-hook-form
  • Clean Code
Aug 2022 - Feb 2023
7 months
Bonn, Germany

Software Developer - Frontend (Freelance)

Deutsche Post IT Services GmbH

  • Actively participated in the agile development process (Scrum) within a multidisciplinary and international team
  • Developed new & existing React components with TypeScript
  • Achieved 80% test coverage with Jest and Playwright, significantly improving code stability and maintainability
  • Efficiently identified and fixed critical bugs
  • Improved app performance through targeted optimizations and refactoring, resulting in faster and more responsive user experience
  • Debugged and verified data in SQL databases
  • JavaScript
  • TypeScript
  • HTML5
  • CSS3
  • Node.js
  • React
  • Redux
  • react-hook-form
  • JIRA
  • git
  • azure
  • swagger
  • playwright
  • Jest
  • TDD
  • REST APIs
  • Code Reviews
  • Clean Code
  • SQL
Sep 2021 - Feb 2022
6 months
Cologne, Germany

Fullstack Developer (Freelance)

myhaircutter.de

  • Designed the architecture for 3 different frontends and a backend with REST API, including data flows
  • Set up CI/CD pipelines and development environment with Github Actions, Docker, Kubernetes, Ubuntu Server
  • Built the frontends using technologies like React, Next.js, TailwindCSS, React Query, Redux, and TypeScript
  • Test Driven Development with Jest and Cypress
  • Developed complex forms
  • Integrated internal and external APIs (e.g., Stripe)
  • Used serverless technologies like cloud functions
  • Developed a Node.js server with features like cronjobs, authentication, and email
  • Deployed, set up & integrated MongoDB as the database
  • JavaScript
  • TypeScript
  • HTML5
  • CSS3
  • Node.js
  • React
  • Redux
  • React-Query
  • JIRA
  • git
  • Github Actions
  • Next.js
  • MongoDB
  • Serverless Cloud Functions
  • Ubuntu Server
  • Styled-Components
  • Cypress
  • Jest
  • TDD
  • REST APIs
  • Express
  • Code Reviews
  • Clean Code
Aug 2019 - Aug 2021
2 years 1 month
Cologne, Germany

Software Engineer - Frontend (Permanent)

Toom Baumarkt GmbH

  • Architecture and development of efficient and reusable frontend systems using technologies like React, Redux and TypeScript
  • Played a key role in planning and implementing the migration to a Micro-Frontend architecture
  • Test-driven development using Jest and Cypress
  • Work on a JavaScript backend microservice responsible for server-side rendering of the shop
  • Close collaboration in an international and interdisciplinary team in an agile environment following Scrum
  • Creation, enhancement and maintenance of responsive User Interfaces
  • Ensuring product quality through regular Code Reviews and Pair Programming
  • Brainstorming and evaluating new technologies and tools for the Frontend area
  • Regular bug fixing & refactoring to keep the code quality high
  • JavaScript
  • TypeScript
  • Node.js
  • React
  • Redux
  • JIRA
  • git
  • gitlab CI/CD
  • Micro-Frontends
  • webpack
  • HTML5
  • CSS3
  • Styled-Components
  • SASS/SCSS
  • Cypress
  • Jest
  • TDD
  • REST APIs
  • Pair Programming
  • Code Reviews
  • Agile
  • Scrum
  • Clean Code
  • SQL
Feb 2018 - Jul 2019
1 year 6 months
Cologne, Germany

Frontend Developer (Permanent)

Agentur Brandung GmbH

  • JavaScript
  • Node.js
  • React
  • React Native
  • Redux
  • JIRA
  • git
  • HTML5
  • CSS3
  • Handlebars
  • jQuery
  • Vue
  • Firebase
  • Code Reviews
  • Agile
  • REST APIs
  • Clean Code
Sep 2016 - Feb 2018
1 year 6 months
Mettmann, Germany

Web Developer

ohaweb.design

  • JavaScript
  • HTML5
  • CSS3
  • WordPress
  • jQuery

Skills

  • React (7+ Years)
  • Javascript/es6 (9+ Years)
  • Typescript (6+ Years)
  • Html5 & Css3
  • Redux
  • Styled-components
  • React-query
  • Next.js
  • Graphql
  • Node.js
  • Express.js
  • Mongodb
  • Micro-frontends
  • Webpack
  • Cloud Functions
  • Serverless
  • Bug Fixing
  • Jest
  • Cypress
  • Playwright
  • Git
  • Frontend Architecture
  • Agile Working
  • Jira
  • Scrum
  • Kanban
  • Pair Programming
  • Code Reviews
  • Mentoring
  • Tdd (Test-driven-development)
  • Office Applications

Languages

German
Native
English
Native

Education

Oct 2014 - Jun 2016

Hochschule Trier

Computer Science (Digital Media) · Trier, Germany

Aug 2005 - Jun 2013

Heinrich-Heine-Gymnasium

High School Diploma (Abitur) · Mettmann, Germany

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