React Router Experts in Germany

• Modernization of a large-scale Java enterprise application*

The project is modernizing a complex enterprise application that has grown over many years. The existing Spring-based legacy system runs on Java 8, OSGi, and Eclipse RCP and is being gradually migrated to a modern, maintainable architecture with Java 25 and Quarkus.

Marcus works on analysis, architecture, refactoring, and implementation. One focus is on untangling historically grown structures and dependencies and on building a clean, sustainable Java and Quarkus technology stack.

Tools & technologies: Java 8, Java 25, Quarkus, Hibernate ORM with Panache, EclipseLink, OSGi, Eclipse RCP, Maven, JUnit, Mockito, REST, JSON, Git, Eclipse IDE, IntelliJ IDEA Ultimate, Jira, Confluence

• Moss is a spend-management platform for SMEs that bundles corporate cards, web-based applications and reimbursements, AP/procurement and advanced accounting in one place.
• Splits time across Accounting, Spending and Growth tribes, handling requirements gathering, public product design, coding, testing, debugging and internal apps.
• Participates in development and maintenance of the design system/UI kit and supports tooling, documentation and developer experience.
• Builds form-heavy UIs, drawer-based editing, high-density/resilient tables with server-side filters, pagination, column configurations, CSV/Excel export and bulk operations, all wired for permissions and auditability.
• Works with complex cross-entity relationships without a single-schema solution.
• Uses React, Redux Toolkit, styled-components, react-hook-form, React PDF, Vite, Lokalise, React Testing Library and Playwright.

PLANT-MY-TREE®-per-order

The application enables Shopify merchants to automatically place tree-planting orders for every incoming order. By integrating ecological contributions directly into the purchase process, the manual effort for tracking and billing reforestation initiatives is eliminated. The system increases transparency for end customers through real-time visualizations of the ecological impact directly in the storefront. The architecture is based on a modular monolith with Spring Boot in the backend and an integrated React app inside the Shopify admin area. The solution uses webhooks to capture order data in an event-driven way and integrates the weclapp ERP system for automated monthly invoicing. An app proxy mechanism provides dynamic statistics such as CO2 compensation and planted trees without any performance loss for the merchant shop.

Tasks:

• Design of the modular software architecture based on Spring Modulith to ensure high maintainability
• Development of the event-driven business logic for evaluating Shopify orders via webhooks
• Implementation of automated invoicing by connecting the weclapp REST API
• Building the frontend using React Router and Shopify App Bridge for native integration
• Design of the database model and implementation of the persistence layer with JPA/Hibernate and Prisma
• Integration of internationalization processes for global use in the frontend and email communication
• Automation of deployment processes using Docker and GitLab CI/CD

Project skills: Java 25, Spring Boot, Spring Security, Spring Modulith, Hibernate, JPA, REST API, PostgreSQL, Maven, Liquibase, React, TypeScript, React Router, Vite, Node.js, Prisma, Zod, Docker, Docker Compose, GitLab CI/CD, Shopify CLI, Shopify App Bridge, Polaris, weclapp, i18next, Lombok, Vitest

• Designed and developed a high-performance internal resource management platform using React and TypeScript, optimizing dynamic data rendering and state management.
• Built a React Native application to support mobile access to internal tools, enabling on-the-go project tracking for field teams.
• Developed custom 2D canvas-based visualizations using Pixi.js to simulate material flows and refractory layer behaviors.
• Integrated Pixi.js with React components for interactive diagrams and real-time UI updates.
• Developed interactive 3D visualizations using React.js for displaying refractory product layouts and simulations, supporting engineering and sales teams with dynamic product previews.
• Integrated Three.js within the React ecosystem to allow manipulation of 3D models in real-time via browser, enhancing user engagement and field configurability.
• Integrated a headless CMS to enable dynamic content updates by non-technical users, reducing content deployment time by 40%.
• Led AWS CloudFront optimization initiatives, improving portal load speeds by 30% globally.
• Actively collaborated with cross-functional Agile teams and product owners to deliver prioritized features with a fast feedback loop.
• Key Technologies: React.js, React Native, Three.js, TypeScript, Contentful CMS, AWS S3/Lambda/CloudFront, Cypress, Agile Scrum

• Significant enhancement of the B2B React SPA software "opti.node" for commercial operations management for renewable energy plant operators
• Introduced features not previously available on the market, resulting in a significant revenue increase
• Comprehensive automated tests within Storybook
• Introduced a UI library to improve developer experience and speed up feature development by about 40%
• Clear presentation of complex commercial and legal issues, with intuitive UX and UI
• UX consulting to shorten essential interaction flows by 75%

• Development of a test system
• Establishment of the architecture using Scala/Java for the backend and Swing for the frontend
• Setup of CI/CD pipelines with Jenkins for continuous integration, including automated builds
• Participation in the Scrum team, including daily stand-ups, sprint planning, and retrospectives
• Technology environment: Scala, Swing, EJB, JPA, Scrum, PostgreSQL, Mercurial

• Development of a CMS-based online platform as a central hub for multimedia brand communication, focusing on accessibility, web performance, and data protection.
• Technologies: PHP, Craft CMS, Twig, HTML, CSS, JavaScript, Alpine.js, htmx.

• A full-stack React CRUD web application for managing cocktail recipes, developed by Kelechi Ibeleche and Fabian Dietrich as part of the Ironhack Web development Bootcamp
• The app allows users to create, read, update, and delete cocktail recipes using a mock backend API
• Served as a practical exercise in React development, routing, and RESTful API integration

• Developed a web application for freelancers: client, invoicing and contract management
• Planned and implemented the complete frontend architecture with React & TypeScript
• Performance optimization: reduced load time by about 40%
• UX/UI: intuitive and clear user interface, improved user flow
• SEO: technical optimization for better visibility
• Integrated external APIs and Supabase storage for PDF generation and document management
• Outcome: fully self-implemented project, stable and scalable platform ready for commercial use

• Development and support of UI and interface by using React JS, Redux, Hooks, TypeScript, NodeJS, JavaScript
• Worked on front-end components and UI tests with Jest and Enzyme
• Worked on REST API using Go and GraphQL
• Implemented efficient and optimized code for improved website performance
• Integrated code quality tools: ESLint and Prettier
• Used Docker, GitHub Actions for CI/CD, Jira, AWS, and Elasticsearch