REST API Experts in Cologne

Project: Introduction of statutory-compliant electronic invoicing (outbound, Germany) in SAP for an international technology group.

• Project management: Planning, steering and reporting of the E-Invoicing outbound rollout across all affected business areas, including budget and resource coordination.
• UAT: Structured user acceptance test with key users per business area, test cases per invoice scenario, and consolidated test results for decision making.
• Defect management: Handover and tracking of defects in Jira, including validation of the generated invoices against the statutory schemas.
• Cutover, go-live and hypercare: Readiness checks and cutover planning aligned with the statutory deadlines, coordination of go-live and stabilization during hypercare.
• Stakeholder management and reporting: Alignment with Finance, Tax, business departments and IT, preparation of status reports and decision papers, and consistent follow-up of open items.
• Change management and documentation: Communicated process changes to the business departments, enabled key users, and created process and compliance documentation to ensure traceability and audit readiness.

• Overall responsibility for platform transformation across ERP, CRM, PIM and AI-supported process automation
• ERP transformation: Introduction and migration to Microsoft Dynamics 365 Business Central
• CRM & Growth Stack: Implementation of HubSpot as the central CRM and platform for lead and marketing automation
• Product data & Commerce Enablement: Introduction of an ePIM to scale Category Management and digital Commerce processes
• AI-supported process automation: Design and introduction of agent-based AI workflows to automate processes in Business Services, Accounting, Tender Management and Marketing
• Building a scalable platform organization consisting of Product Development, DevOps, UX, Cloud Engineering and Corporate IT
• Introduction of modern product and portfolio governance (e.g. OKRs, portfolio boards, value-based roadmaps) to manage technology-driven initiatives
• Harmonization of heterogeneous system landscapes and transformation into a modular, scalable platform architecture (ERP, CRM, PIM, integrated customer journeys)
• Coaching and development of Product Owners, Tech Leads, Delivery Managers and UX teams in building a scalable product organization

With project PRIZMA, DB will modernize its infrastructure on the one hand, and develop a fail-safe IT landscape on the other hand, which can be restored quickly and securely in case of a disaster.

• Capture current architectures of existing systems as well as methodical consulting and development of target architectures
• Deepen and maintain the building plan / target IT landscape
• Implement technical architecture concepts & architecture descriptions
• Implement migration concepts for updating and further developing the platform and information systems
• Assess submitted improvement suggestions as part of the project
• Capability management: identify capability gaps, develop target visions, and support transformation planning within the enterprise architecture.
• Create a compatibility matrix of the components in use and compare dependencies of specific versions
• Create an IT concept for extending the platform with the following topics: hardware and software requirements, security, licensing, high availability, load balancing, backup & recovery, update strategy, monitoring integration, etc.
• Coordinate with business architects as well as technical architects from the cross-functional architecture area of the PRISMA program for the topics (backup, Active Directory, monitoring, Citrix, and business applications ...)
• Status meetings and alignment of project planning with the Release Train Engineer / Project Manager
• Advise the Release Train Engineer / Project Manager in identifying project risks
• Advise the System Architect Engineers in steering the implementation of the concept
• Implement the IT concept
• Document the infrastructure

Label: MS Project, LINUX, Windows, ORACLE, Java, REST, SharePoint, Microsoft Exchange, UML, Enterprise Architect, BPMN, AZURE, AWS, V-MODEL, Micro Service, VisualStudio, SAP S/4HANA, SCRUM(SAFE), ESB (TIBCO), Python, Innovator, LeanIX (TOGAF), Ansible, Ansible Tower, Ansible Automation, ROBOT, SpringBoot

• Planning and implementation of a migration strategy for master and transaction data for the continuous loading of a cloud-independent database
• Creation and pilot implementation of a company-wide Business Data Model for customers, suppliers, contracts, products, prices, consumption, invoices, and dunning
• Concept and consulting for a Data Governance Framework incl. definition of committees, roles, processes, and metadata model
• Operationalization of the Data Governance Framework with definition of data standards
• Sub-project management in two pilot projects (PoCs) for Data Governance systems (ErwinDIS and Atlan)
• Training and coaching the data team in migration, data quality, and data modeling

• Structured analysis and evaluation of business processes

• Gathering, documenting, and prioritizing requirements

• Creating business-friendly and technically executable process models

• Use of Camunda tools

• Deriving requirements and interfaces from BPMN diagrams

• Coordination with stakeholders and business units

• Translating business requirements into technical solution designs

• Implementing efficient and tailored applications

• Systematic collection, analysis, and documentation of requirements

• Prioritizing and validating requirements in close collaboration with stakeholders

• Alignment between business and development to ensure shared objectives

• Creating use cases, user stories, and acceptance criteria

• Continuous requirements and change management throughout the project lifecycle

• Define project goals and create project plans

• Delegate tasks and monitor project progress

• Monitor budgets and inform stakeholders

• Mendix: Architecture, development, and maintenance of custom applications (Microflows, Domain Model, Security, XPath)

• Modeling Mendix workflows for process optimization

• Develop scalable apps with Mendix including REST/SOAP integration with SAP, SQL, Azure & SharePoint

• UI design for Mendix using Atlas UI, Fluent UI, HTML, CSS, JavaScript

• Develop web & mobile apps with Mendix using agile methods (Scrum, Kanban)

• Implement business logic with Mendix Microflows and Nanoflows

• Performance optimization and architecture improvements for Mendix applications

• Conduct Mendix training

• Create technical documentation and best practices for Mendix

• Coaching and mentoring for low-code development with Mendix

• SPA for automated communication of medical findings with role-based access (Sanctum)
• Server-side LLM integration (OpenRouter) with structured processing
• Automated sending via SMS/voice call (Twilio, ElevenLabs) with queue + status retry
• Full test coverage with 80+ documented test cases

Technologies: PHP, Laravel, LLM API (OpenRouter), Twilio, ElevenLabs, Laravel Sanctum, PHPUnit, Playwright, Docker, REST

• Led the end-to-end architecture and migration of a legacy on- premise IoT monitoring system to a cloud-native Azure platform within a 17-member development team
• Designed and implemented a scalable microservices architecture (Java 21, Spring Boot, Kubernetes, Azure Services), decoupling IoT data streams and eliminating legacy system bottlenecks
• Defined technology stack, mentored developers, and orchestrated cross-functional teams in 4 countries to ensure high-quality delivery and alignment with architectural standards
• Drove requirements engineering and system redesign, removing years of technical debt and introducing event-driven processing and automated workflows
• Key Achievements
• Increased system stability and uptime by ~10x, eliminating need for 24/7 DevOps intervention
• Reduced hosting costs by ~80% (5x savings) through cloud optimization
• Improved performance and scalability, enabling stable handling of high-volume IoT data streams
• Delivered successful zero-disruption migration from on-prem to cloud, with strong user satisfaction and reliability from day one

Technologies: Java 25, Selenium, Insomnia, SSO, Gitlab, Jenkins, Docker, Kubernetes, Jira, IntelliJ, Nexus, Oracle, MariaDB, SpringBoot, Grafana, Concept Board, Vue.js, OpenApi, Kotlin. Implementation, maintenance, and enhancement of automated end-to-end regression tests for UI and API interfaces. Appropriate and targeted test automation involving multiple software products, including Java-based Windows applications. Automation of business processes with Selenium, reset jobs, and DB import jobs, as well as creation of test concepts, test case descriptions, and structured defect reporting.

• Created an application to control measurement hardware with a Tauri application using React.JS and TypeScript on Raspberry Pi
• Developed a cloud application for storing and analyzing measurement results using Spring Boot and React.JS
• Built a Tauri application for printing ZPL labels on Windows
• Technologies: Java, JavaScript, Tauri, Rust, React.JS, AWS, Kubernetes, Docker, GitLab CI/CD, REST API (JSON), Maven, CI/CD, PostgreSQL

• PHP 8.4
• Platform for prize draws: API-first approach with Symfony/API Platform
• API Platform 4.2 (REST, JWT, Doctrine/PostgreSQL, API documentation) plus AWS tools
• Symfony 7.3 for infrastructure, hosting, and subsequent operation on AWS with ECS
• Postgres
• AWS RDS, SQS, Fargate, RDS Postgres database, and AWS-SQS message queue
• Infrastructure management with Terraform
• After successful Terraform implementation, the next organizational step is to establish a GmbH

• Perform secure code reviews and provide secure-coding guidance across the application and platform architecture.
• Engineer infrastructure security and design security-monitoring architecture, incident-response playbooks and Security-by-Design controls.

• Built more than 15 frontend applications and more than 10 backend services across internal tools, back-office workflows, and external portals for installers and end customers
• Automate build and release workflows with TypeScript and Azure DevOps
• Mentor junior engineers through code reviews and technical guidance
• Integrate AI-assisted and agentic development practices into engineering workflows
• Coordinate user experience decisions with UX designers

Tech Stack: Claude Code, Codex, AWS (S3, Lambda, AppSync, Resolver), Next.js App Router, ReactJS, NuxtJS, Vue.js, Storybook, JavaScript, TypeScript, GraphQL, Azure DevOps

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

• Concept for database major / minor release automation

• Assessment of the current state

• Evaluation of Redgate Flyway functionalities

• Concept development

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

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

• Developed a SCIM-compliant Python interface to connect external systems
• Expanded and enhanced UCS modules in Python
• Extended and newly developed Helm charts for container orchestration in Kubernetes
• Maintained and further developed CI/CD pipelines in GitLab
• Implemented automated tests with Pytest and Playwright

'Nubus' is based on a microservice architecture, relies on open source technologies, and runs in Docker containers.

UCS is an IAM complete solution based on Debian, used as an alternative to Microsoft's Active Directory. The work was characterized by the close integration of infrastructure and application logic.