Hi, I am Marc

Responsibilities:

• Contributed to a greenfield, event-sourced platform that serves as the system of record for property units and the full lifecycle of their metering devices (installation, replacement, removal)
• Part of the team building the backend in Kotlin on Spring Boot 4 / Java 25, running in production on Azure Kubernetes Service
• Domain-Driven Design enforced at build time (hexagonal architecture and DDD building blocks validated by jMolecules and ArchUnit), so an architecture violation fails the pipeline instead of slipping through review
• Event Sourcing and CQRS on a PostgreSQL event store (state is rebuilt by replaying domain events), which gives a complete and auditable history of every device change instead of overwritten rows
• Anti-Corruption Layer that keeps the core domain clean (consumes work orders from Azure Service Bus, validates and transforms legacy formats into domain events, and integrates SAP via OData and SOAP)
• Contract-first API design with OpenAPI 3 and JSON Schema as the single source of truth; API clients and event classes are generated from the contracts, so services cannot drift apart
• Testing across the pyramid (unit and integration tests with JUnit 5, Mockito, WireMock and Testcontainers, plus a Cucumber / REST Assured BDD suite that verifies business processes end to end)
• GitOps delivery (GitLab CI builds and versions the service, ArgoCD syncs Helm charts to AKS; SonarQube, Spotless and OpenRewrite gate every merge)
• AI-assisted development as part of daily delivery (Claude Code with custom agent skills and automated review loops for code review, test generation and repetitive refactorings), with every change still reviewed by a human before merge
• Kotlin, Java 25, Spring Boot 4, Event Sourcing, CQRS, DDD, Hexagonal Architecture, PostgreSQL, Flyway, Azure Service Bus, CloudEvents, SAP OData/SOAP, Docker, Kubernetes (AKS), Helm, ArgoCD, Terraform, GitLab CI, JUnit, Mockito, Testcontainers, WireMock, Cucumber, OpenAPI 3, Maven, Claude Code

Responsibilities:

• Built and maintained the shared CI/CD platform (reusable GitLab CI pipeline templates and Infrastructure-as-Code modules that development squads adopt instead of writing their own)
• Defined the cloud architecture for centralised and squad-specific DevOps use cases on Azure
• Set up and operated the development, test and production environments, including the tooling around them
• Consulted and mentored development teams on their application lifecycle, with a focus on CI/CD
• Azure, GitLab CI, Terraform, Kubernetes, Helm

Responsibilities:

• Migrated the service landscape from Docker Swarm to Kubernetes and moved on-premise applications to Azure, while the services kept running for the business that depended on them
• Replaced manual data consolidation across several source systems with Spring Boot integration services feeding one central system
• Decoupled services that had been calling each other synchronously, using JMS on ActiveMQ and Spring Batch for the work that belonged in a batch
• Designed and documented the REST APIs contract-first with OpenAPI 3.0, so the consuming teams stopped guessing
• Developed the matching Angular frontends and covered the backends with JUnit and Mockito tests
• Java, Spring Boot, Docker, Kubernetes, Hibernate, Liquibase, Angular, GitLab CI, JUnit, Mockito, Spring Batch, Azure, Maven, MariaDB, PostgreSQL

Responsibilities:

• Built business and integration services in Java EE and Spring Boot, deployed as containerised microservices
• Designed entity relationship models and optimised complex queries
• Implemented synchronous and asynchronous interfaces, using REST (JAX-RS, JSON), SOAP (JAX-WS) and messaging via JMS/ActiveMQ
• Built high-volume, low-latency services and verified them under load with Gatling.io and JMeter
• Applied object-oriented analysis and design with common design patterns, and supported the build and deployment process
• Java, Spring Boot, Docker, Hibernate, Flyway, GitLab CI, Spock, Kubernetes, AWS, Maven

Responsibilities:

• Designed and built a microservice architecture for route planning, from the first MVP to production
• Set up the CI/CD pipelines and the delivery process for the new service landscape
• Built up the development team (first nationally with external contractors, then a permanent team of six developers in Poland)
• Handed the project over to the team in Poland and established a lead developer role there
• Java, Spring Boot, Docker, Hibernate, Flyway, GitLab CI, Spock, Kubernetes, AWS, PostgreSQL, Maven

Responsibilities:

• Designed and built a service layer in front of a legacy application, so new applications could integrate against a modern API
• Worked in a team of four developers in Essen and delivered the project on schedule
• Java, Spring Boot, Docker, Hibernate, Flyway, GitLab CI, JUnit, Kubernetes, AWS, Vue.js, Netflix Stack, PostgreSQL, Maven

Responsibilities:

• Supported the company-wide initiative to move Schenker applications to AWS, in a team of ten developers in Essen
• Built the AWS VPC foundation and provided hardened AMIs for the application teams
• Containerised legacy applications and provided the supporting Docker images for the CI pipelines
• Kubernetes, Docker, Terraform, Packer, GitLab CI, Ansible, Python, Spring Boot, Oracle, PostgreSQL

Responsibilities:

• Built a self-service portal for Atlassian Confluence and Jira, so teams could request spaces and projects without a ticket to IT
• Java, Spring Boot, Gradle, Vue.js, npm

Responsibilities:

• Supported the development of a self-service portal for an identity and access management (IAM) application
• Worked in an international team of five developers together with colleagues in China
• Java, Spring Boot, Maven, AngularJS, Oracle

Responsibilities:

• Administered the server infrastructure and the directory services behind it
• Supported end users across the authority as second-level support
• Debian Linux, Windows Server 2000, LDAP

Responsibilities:

• Completed the apprenticeship as IT specialist for system integration (Fachinformatiker Systemintegration)
• Worked across server administration, directory services and end-user support
• Debian Linux, Windows Server 2000, LDAP