AJAX Expert in Germany

• Implementation of a full-stack application with Angular as frontend framework and Java as backend language
• Use of the Swagger OpenAPI specification for REST communication between frontend and backend applications
• Control of a card printer via the Nexus Card SDK framework
• Design and implementation of card management software with web interface and JavaFX module for printer monitoring
• Use of Cucumber tests for test automation and creation of test artifacts for testing outside the development environment
• Use of Wireshark for network investigations to analyze the API of a third-party product and to check the REST API of the self-developed software

• 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

Oracle Project Management and Automation

As part of the project, the operation of an Oracle infrastructure was automated by developing and enhancing Puppet modules and migrating existing Bash scripts to a standardized configuration management solution.

The aim of the project was to standardize and automate administrative processes, improve the maintainability of the Oracle platform, and increase the efficiency and traceability of infrastructure management through the use of Infrastructure as Code.

• Analysis and migration of existing Bash shell scripts to a Puppet-based automation solution
• Development and enhancement of Puppet modules for Oracle environments
• Automation of installation, configuration and operational processes using Infrastructure as Code
• Standardization and optimization of configuration management for Oracle systems
• Creation and maintenance of technical and operational documentation
• Planning, coordination and professional support during project implementation
• Operation and automation of Oracle systems on x86-based Linux server platforms
• Testing and quality assurance of the developed Puppet modules
• Analysis and resolution of technical errors as part of the automation and migration
• Close coordination with specialist departments and infrastructure teams to implement automation requirements

Technologies used: Puppet 7/8, SLES 15, Oracle 19, Oracle Grid, SVN, Windows Server, Confluence, VS Code, Ruby, Bash, Pass

• Designing the audit logging framework
• Implementing APIs for developers to integrate in their codebase
• Implementing ingestion pipeline, database query layer and UI for browsing the audit events
• Improving stability and reliability of the backend system

• Developed a new web app to manage and configure counting devices for large events
• Technologies: .NET 10, C#, Blazor, MudBlazor, MySQL, Git

Tasks

• Further development of a new ERP system with Blazor
• Generation of e-invoices in the XRechnung and Zugferd formats
• UI/UX design Client-server system
• Windows 11 Technology
• Microsoft .NET 9, Git, Azure DevOps, ASP.NET, MSSQL, Blazor Programming languages
• C#, MVVM Development tools
• Microsoft Visual Studio .NET 2022 Database
• MSSQL Industry
• Other

• The goal of BIENE is to provide a unified tax collection program for all federal states.

• Tax collection involves collecting the taxes that have been assessed. This includes, for example, taking due dates into account, recording incoming and outgoing payments, and initiating reminders or refunds. Limitation periods and payment reminders are also important. BIENE handles all payment transactions with banks and accounting.

• Set up the architecture and coordinated the provision of development and test environments at the Hannover site

• Installed and configured the environments on Linux servers (Apache Kafka, PostgreSQL)

• Interface coordination: coordinated and aligned the connection of software products from other departments and their test data

• Migrated the application server, JDK, and Maven project structure

• Coordinated environments and managed builds

• Implemented external interfaces

• Delivered business requirements

• Designed and implemented RESTful APIs and OpenAPI specifications

• Designed and implemented a microservice architecture

• Set up and maintained CI/CD pipelines

• Deployed applications on OpenShift

• Created technical documentation and diagrams

• Worked with SQL databases (Oracle and PostgreSQL)

• Set up authentication and authorization for the application and users

• Containerized the application (automated deployment through the CI/CD pipeline)

• IT training in theory and practice for IT specialists in application development and system integration

LOIS is the central integration platform that enables the processes between all REWE applications across the entire supply chain. As an IT Business Engineer, I support the NEO program in renewing the logistics integration platform "LOIS" for REWE and Penny in Germany and Europe.

• Supporting several agile teams in the new product development of an enterprise CRM and ERP application
• Web frontend development with Angular 17–21 (microfrontends, Domain-Driven Design, MDB-Bootstrap)
• Backend development with C# and .NET 7–10, MongoDB, MassTransit, RabbitMQ, Entity Framework Core, ElasticSearch (microservices, DDD)
• Technical feature design for assigned tasks
• Technical architecture design including forward-looking planning of AI-supported extension options
• Proof-of-concept implementation of AI-supported workflows with n8n and a locally hosted LLM (Ollama)
• Coordination with stakeholders and Product Owners, support with sprint planning

Result: Delivery of production-ready microservices and frontend modules in agile sprint cycles.

Environment: .NET 7–10 · Angular 17–21 · C# · TypeScript · OpenAPI · Microfrontends · DDD · Kubernetes · Docker · Helm · MS SQL Server · PostgreSQL · MongoDB · MassTransit · RabbitMQ · EF Core · ElasticSearch · Kibana · Azure DevOps · KeyCloak · n8n · Ollama

• Selection and evaluation of different frontend frameworks for a headless CMS

• Consulting the UI/UX team on the design system

• Technologies:

• Figma

• Design Token

• Tailwind

• Storybook

• React

• NextJs

• Strapi

• AJAX

• Confluence

• CSS3

• Docker

• Eslint

• Git

• GraphQL

• HTML5

• IntelliJ/WebStorm

• JAM Stack

• Jasmine

• Jenkins

• Jira

• JSON

• JSX

• Mocha

• Native JavaScript (ES6)

• NodeJS

• Prettier

• REST

• REST APIs

• SCSS

• SSR

• StyleGuides

• SVG

• TypeScript

• Webpack

• Contributed to the development of an advanced RAG AI Chat application that integrates multiple LLM models, enabling users to seamlessly switch between models based on specific tasks. This improved the user experience by providing tailored, efficient solutions for various use cases, such as event scheduling, booking systems, and complex task management.
• Participated in designing and implementing a robust backend architecture using Spring AI, enabling advanced AI-driven capabilities like intelligent task automation, language processing, and contextual recommendations. Leveraged Spring AI Tools and Advisors to enhance the performance and decision-making of the AI models.
• Collaborated on the integration of vector databases to support embeddings, enhancing the app's ability to understand user queries and perform actions based on complex, real-time data inputs.
• Contributed to the development of a seamless, user-friendly front-end interface using React with TypeScript support, ensuring a modern, responsive, and scalable user experience across platforms.
• Assisted in implementing state management with Redux RTK for efficient data flow and real-time updates, optimizing the overall user experience in dynamic scenarios such as scheduling and task management.
• Partnered with stakeholders to define feature requirements, helping ensure that the app could scale to meet evolving business needs and integrate with other systems like calendar and email services. Worked alongside cross-functional teams, including data scientists and UI/UX designers, to fine-tune AI models and ensure alignment with project goals.
• Contributed to ensuring end-to-end system performance, security, and compliance by helping integrate authentication mechanisms, role-based access control, and secure communication protocols in both backend and frontend layers.

Technology Stack and Key Contributions:

• Java / Spring Boot / Spring AI: Developed backend services leveraging Spring AI for intelligent responses, task automation, and complex workflows.
• React / TypeScript: Built intuitive user interfaces with React and TypeScript, ensuring a smooth and scalable frontend.
• Redux RTK: Managed application state with Redux RTK for optimized state management, enabling dynamic, real-time data updates.
• Vector Databases: Integrated vector databases (pgVector) for embedding support, improving AI model performance in handling complex queries.
• PostgreSQL / Redis: Managed persistent and temporary data with relational and in-memory data stores, ensuring data integrity and speed.
• Kafka: Utilized Apache Kafka for event-driven communication and seamless integration between microservices.
• Spring Security: Ensured the security of backend services with robust authentication and authorization mechanisms.
• CI/CD & DevOps: Integrated continuous integration and deployment pipelines to ensure rapid and secure deployment of features and updates.

• Consulting and creation of various web applications based on SharePoint and the React framework for different clients
• Development and testing of accessible apps for SharePoint
• Creation of various test cases for test automation
• Development of various solutions based on Azure
• Creation of various web services based on .NET
• Development of various SharePoint Framework solutions
• Development of various UI solutions based on SharePoint
• Consulting and creation of various Power Apps applications and Power Automate for the steel industry and an IT consulting company
• Support, consulting, and development with offshore teams for SharePoint 2013, 2016, and microservices for a logistics company
• Consulting, concept design, and development of microservices and web applications based on Microsoft technology and the React framework for a logistics company
• Consulting, concept design, and development of various SharePoint Framework solutions on SharePoint 2016 for logistics
• Consulting for the migration from SharePoint 2010 to 2016 for an IT consulting company

• Consultant for system architecture, AI agents & integration, coach for data & process logic, Graph-RAG approaches, security and data protection.
• On-premise AI solutions with high compliance and performance requirements.
• Architecture decisions, operational setup, strategic prioritization & deployment.
• Technologies: LiveKit JS SDK, LiveKit Agents, Web Audio API, JS, AudioWorklet, Loki, vLLM, Zscaler, Docker, Neo4j, MySQL, Python.
• Models: GPT-OSS 20B, Whisper large v3 turbo, Qwen3-TTS.