Software Developer in Cologne

• Self-hosted table tennis equipment platform.
• Development of a custom “Racket Builder” that uses a co-evolutionary genetic algorithm to identify, evaluate, and recommend the optimal combinations of racket blades and rubbers based on physics heuristics and player data within a search space of over 4 billion combinations.
• Development of a custom fully automated web crawler to capture equipment specifications, integrating an automated pipeline for image normalization as well as data harmonization via DeepSeek.
• Cloudflare Edge Workers written in Rust to perform low-latency data searches and offload computationally intensive simulations from the main server.
• High performance and accessibility standards across a large Nuxt 4 codebase achieving 95–100/100/100 Lighthouse scores.

PLANT-MY-TREE®-per-order

The application allows Shopify merchants to automate tree-planting orders for each incoming order. By integrating ecological contributions directly into the checkout process, manual work 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 for event-driven capture of order data and integrates the ERP system weclapp 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 using 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, 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

• Built a modular C++ 20 embedded Linux acquisition system on a Raspberry Pi, synchronizing IMU and dual-camera data streams to sub-millisecond accuracy.
• Integrated retro-reflective and contrast sensors to trigger acquisition and detect gaps between sorter rails.
• Implemented SPI & I2C sensor communication, GPIO interrupt handling with libgpiod, and CSV & JSON output.
• Designed a multi-threaded acquisition pipeline and an SPSC queue between acquisition and writer threads.
• Built a Python/HTML/CSS based web-server and validated the prototype in a DHL warehouse for defect detection.
• Documented software behavior, configuration, and results for maintainable handover and further development.

• Automation of the database major / minor releases for the TKeasy project

• Concept for database major / minor release automation

• As-is analysis

• Evaluation of Redgate Flyway functionality

• Concept creation

• Products: Redgate Flyway, GitHub, Quest, Erwin Data Modeller, Oracle, Atlassian Jira, Atlassian Confluence

• Skills: Docker, Continuous Delivery, Continuous Integration, Redgate Flyway, Major Releases, Minor Releases

• Tested integration of TIBCO EBX with SAP S/4HANA via TIBCO BusinessWorks – proof of concept
• Implemented use case: communication between TIBCO EBX and SAP S/4HANA via IDocs to exchange material master data and business partner data
• Customized, configured, and implemented inbound and outbound processing in the SAP S/4HANA environment for communication with the TIBCO EBX software interface
• Distributed classes, characteristics, and values between TIBCO BusinessWorks and SAP S/4HANA and customized the inbound processing
• Documented the technical components

• A warehouse valuation system was reimplemented using Java, Spring Boot, and Camunda. The backend solution focuses on integration and batch calculations, the frontend on managing formulas and reviewing results.
• Java 21
• Spring Boot
• JPA
• Maven
• REST
• Kafka
• PostgreSQL
• DB2
• Liquibase
• Google Cloud Storage
• Keycloak
• GitLab CI/CD
• Helm
• Terragrunt
• SonarQube
• Angular
• IntelliJ
• JUnit 5
• Mockito
• Open API

• Developed a shop website
• Integrated an AI language model
• Developed tools for AI-powered webhooks
• Technical tools: REACT.js; Elevenlabs; MCP; n8n; HTTP

• Web development with Blazor
• Two-factor authentication for Blazor applications
• Uploading and downloading files
• Bug fixes for existing applications
• Programming interfaces
• Integration of third-party tools and technologies
• Creation of developer tests (unit tests)

• Process optimization
• Productivity increase in production
• Lean management
• Shopfloor management
• Production management
• Production control and planning
• Outsourcing
• Leadership training
• Private coaching
• Career coaching
• Self-management training
• Heidenhain, Siemens, Millplus
• CAD design with Fusion 360, SolidWorks
• FDM
• SLA
• Product design
• Prototyping
• Series production

Technologies: Java 25, Selenium, Insomnia, SSO, GitLab, Jenkins, Docker, Kubernetes, Jira, IntelliJ, Nexus, Oracle, MariaDB, Spring Boot, Grafana, Concept Board, Vue.js, OpenAPI, Kotlin. Implementation, maintenance, and extension of automated end-to-end regression tests for UI and API interfaces. Appropriate and targeted test automation across multiple software products, including Java-based Windows applications. Automating business processes with Selenium, reset jobs, and DB import jobs, as well as creating test concepts, test case descriptions, and structured bug reporting.

• Evolved the platform from bare-metal infrastructure with a monolithic PHP application to a hybrid Google Cloud architecture with Go microservices on Kubernetes
• Managed and scaled a production infrastructure with 300+ VMs and dozens of clusters, including MySQL, PostgreSQL, MongoDB, RabbitMQ, Redis and Elasticsearch clusters
• Designed architecture, deployment, monitoring, performance analysis, and upgrades for all platform services using Terraform and Ansible
• Migrated observability systems from ELK and Prometheus to Datadog, managed with Terraform
• Introduced Jenkins CI/CD with SonarQube integration and automated tests to speed up feedback cycles
• Containerized the testing environment and implemented GitLab CI pipelines for Docker image builds, static code analysis, and infrastructure tests
• Performed zero-downtime migrations of MySQL and MongoDB clusters to Google Cloud
• Developed reusable Ansible roles for database clusters and automated data obfuscation for staging environments
• Decomposed monolithic databases and migrated to microservice architectures
• Built tools to detect and optimize slow queries in MySQL and MongoDB
• Conducted online schema migrations with pt-online-schema-change without downtime windows
• Developed internal Go applications for batch queries, GitLab-Jira integration, and MongoDB backup recovery
• Technologies: Debian, Ubuntu, Alpine, Go, Bash, Python, PHP, SQL, GitLab CI, Jenkins, Drone CI, MySQL, MongoDB, PostgreSQL, Redis, Elasticsearch, RabbitMQ, Kafka, Docker, Kubernetes, Nomad, Ansible, Terraform, Grafana, ELK, Prometheus, Datadog, Nagios, Zabbix, Nginx, HAProxy, Vault, Helm, SonarQube, Filebeat, Auditbeat, Google Cloud, AWS

• Two-month modernization of the management UI for AI-powered cameras
• Rewrote a complex React application to Vue 3 with single file components
• Set up the core architecture of the Vue application and configured Vite, Pinia, Router, I18n, ESLint, and Prettier
• Custom integration of Leaflet to display detection zones on images
• Assisted with backend extension and authentication adjustments

• In-depth forensics of old and new data sources
• Enhancing existing reports and creating new data analyses
• Data preparation from source systems and semantic models
• Azure DevOps integration
• Tools/Skills: MS-PowerBI, DAX, MS-Office 365, PowerQuery, M, PowerAutomate, Redmine, SharePoint, SQL (T-SQL, Oracle), MS Fabric

• Support and further development of a framework for developing applications in a banking association: DynS/OSPE
• Migration of the framework to Java 11 and Java 17
• Java8, Java11 and Java17, Spring, Spring-Batch, Spring WebServices, Spring-Security, Spring-Data, JPA, Hibernate, OpenSource libraries etc.
• XML, JAXB, JSON, REST and SOAP services, DB2, Oracle, WebSphere or Liberty AS, FreeMaker, Junit, mock libraries, JaCoCo, Maven, IntelliJ, Eclipse, GitHub, SVN, Jira