Spring Framework Experts in Munich

• 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

• 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

• Overall responsibility for the project lifecycle from scope definition to completion
• Close collaboration with platform teams, IT leaders, and external service providers
• Application of SAFe principles and structured sprint work
• Creation of a migration roadmap with clear milestones
• Monitoring of the lifecycle: onboarding, repository migration, replication of permissions, and system tests
• Visualization of the architecture with PlantUML and Gliffy as well as documentation in Confluence
• Regular status reports and running knowledge transfer sessions

• Integrated LangChain middleware between AEM and SAP PIM system
• Developed a FastAPI interface for system communication
• Implemented vector embeddings for semantic product search
• Evaluated LLM models (Vertex AI/Gemini, LM Studio, Hugging Face, OpenAI) for product analysis
• Developed an AEM component to display product recommendations and integrated the recommendation API into the AEM authoring process
• Designed and implemented Pinecone vector database for product embeddings
• Optimized response times and caching strategies
• Evaluated Vertex AI Studio for LLM testing and prompt workflows
• Implemented secure API routing and access control for AI components via FastAPI and gateway validation

• Implementation of a GitLab CI/CD pipeline based on SAP Commerce Cloud 2211
• Development of a new B2C shop with Vue, Node and TypeScript to ensure scalability, extensibility and performance optimization
• Integration of Microsoft Azure Event Grid with SAP Hybris
• Implementation of BDD with Cucumber using Gherkin syntax to promote collaboration between development and business teams
• Support and customization of a Spartacus shop
• Technologies/Languages: Java, REST, OData, Behavior Driven Development (BDD), Cucumber, Node, Vue, TypeScript, Spartacus, GitLab CI/CD, Gradle, Maven, Ant, SonarQube

• Participated in the gradual modernization of components into cloud-native 12-factor applications.
• Worked closely with the business operations team to eliminate manual processes and resolve several performance bottlenecks.
• Designed and implemented a CI/CD pipeline to increase developer productivity, enforce quality and security checks, and automate product delivery.
• Migrated several components into the OpenShift Kubernetes cluster.
• Built a monitoring stack from scratch with Prometheus and Grafana to monitor services running in OpenShift.
• Developed dashboards in both Grafana and Splunk for operational transparency.
• Implemented an OIDC/OAuth2-based single sign-on (SSO) solution with Keycloak to secure multiple applications.
• Technologies: Java, Spring, Quarkus, Kafka, MySQL, Cassandra, Redis, Spring Data, Hibernate, Docker, Kubernetes, OpenShift, Keycloak, OIDC, OAuth2, Helm, Prometheus, Grafana, Splunk, Spark.

• Backend development of B2B e-commerce solution using SAP Commerce Cloud, leveraging Java and Spring Framework with creation of REST APIs for effective communication.
• Resolved software defects, developed automated cron jobs and triggers, and authored unit tests with JUnit to uphold code stability and quality standards.
• Utilized Git-based version control systems (Bitbucket/GitHub) for source code management and used Jenkins to support continuous integration and development (CI/CD).
• Executed and closed multiple user stories and tickets across iterative bi-weekly sprints under Agile (SCRUM) methodology.
• Led incident resolution in the production environment and minimized downtime through real-time monitoring (Solr, SAP CCv2, OpenSearch Dashboards) and sustaining SLA targets above 99%.

I have worked across multiple international client projects, holding senior roles including Software Architect, Senior Software Developer, Technical Lead, and Lead Backend & DevOps Engineer. My experience spans complex enterprise environments in banking, financial services, telecommunications, engineering, and automotive domains, supporting organisations such as UniCredit Bank, Telefónica O2, and BMW.

At UniCredit Bank, within the Securities Domain Transformation program, I led the modernisation of legacy monolithic systems into cloud-native Spring Boot microservices and an Angular frontend deployed on Google Cloud Platform. Beyond implementation, I was responsible for defining the target architecture, producing system architecture diagrams and sequence diagrams, and preparing API contract documentation for clients. I designed RESTful APIs and integrated Apigee for secure and reusable cross-project service consumption of APIs. I architected Kubernetes-based deployments using Helm. CI/CD pipelines were built with Jenkins, automating code analysis using Sonar, as well as testing and deployment stages. Defining clean coding principles for the project, conducting regular code reviews, and mentoring junior developers were also among my tasks at UniCredit.

At Telefónica O2, I led the transformation of a legacy call centre desktop application into a cloud-native microservices and micro-frontend solution. I actively contributed to the platform architecture, creating system architecture diagrams, component diagrams, architecture documentation, and ADRs for future references. I improved the performance and scalability of the services. I optimised AWS infrastructure costs, particularly by minimising the use of DynamoDB and reusing test environments effectively. Observability was implemented using Prometheus, Grafana, CloudWatch, and Splunk dashboards. CI/CD pipelines were delivered using GitLab, Docker, Kubernetes, and AWS. Conducted techinical sessions for teams.

• Create a product and service portfolio delivering a 360 degree approach to digital corporate sustainability covering KPI management, CSRD reporting and sustainable strategy
• Create vision and business case
• Onboard and align business partners, negotiate contracts
• Set up partner network as self-organized agile team
• Co-develop product and service portfolio
• Coordinate sales and marketing, go-to-market strategy and roadmap

• Role: Senior FullStack Developer
• Technologies: Google Cloud, Azure, Microsoft Entra, Keycloak, Spring Boot, Java
• Active in production

• Act as interface between business, IT demand management and IT architecture, analyzing functional and technical requirements in Salesforce.
• Create requirements and specification documents together with the business unit and develop solution concepts.
• Define, control implementation and acceptance of epics and user stories.
• Advise business units on optimization potentials and develop functional solution concepts.
• Support project management and product owners in scope analysis and ticket creation.
• Develop identity management solutions and deletion concepts in the Salesforce environment.
• Define and implement DWH reports for analysis of business areas and process optimizations.
• Document and optimize functional process workflows.
• Tools and technologies: Miro, Salesforce, Draw.io, Atlassian Stack (Confluence, JIRA), Figma, Enterprise Architect, MS Teams, Slack, Zoom, SCRUM, agile project management.

• Requirements analysis and planning of the software architecture
• Analysis and design of REST APIs
• Backend development with Java 17, Spring Boot, Spring MVC, and Spring Data
• Frontend development with Angular and TypeScript
• Setting up CI/CD pipelines
• Code review, QA, and testing
• Using MySQL, Docker, the ELK stack, and RabbitMQ

• Further development of the vergleich.de website

• Development of new and improvement of existing backend services as microservices

• Deployment via TeamCity and GitHub Actions

• Development of monitoring tools

• Development of REST APIs

• Database migration from Oracle to PostgreSQL

• Java and Kotlin (including Spring, Spring Boot, JPA, Hibernate)

• Angular (TypeScript) and JavaScript

• IntelliJ IDEA and WebStorm

• Apache Maven

• Oracle DB (and SQL Developer), MongoDB, PostgreSQL DB

• Git (GitLab, GitHub, BitBucket)

• TeamCity

• Jira

• Docker

• JUnit, Mockito, jasmin

• Platform: Python ecosystem, RHEL 8, K10, AWS IoT Core, AWS Lambda, MLOps
• Software: Java JEE/cloud, IntelliJ IDEA, AWS IoT Core, AWS Edge and Lambda, AWS SageMaker SDK, Docker Compose, Kubernetes, OpenShift 4, Tekton, Flux, Helm charts, JSON/XML technology, Nginx, Apache Spark, OpenAI (GPT Plus, DALL-E 3, Whisper), GAN, GitHub Copilot, AI/machine and deep learning, Jupyter notebooks, TensorFlow 2, Colab, Keras API, Prometheus, Grafana, Conda, Python 3.9, PySci stack (NumPy, pandas, Scikit-learn, matplotlib)
• Responsible for webinar:
• IoT edge computing: architecture, components, resources, management
• IoT edge computing with MicroK8s, designing and creating flows/diagrams for AWS, three-step model for IoT ecosystem
• IoT processes, connectivity, data transfer and deployment, security
• Optimization of edge computing for IoT networks and services (AWS SQS queue, SNS notifications, events, analytics, buttons, device management/defender, Things Graph)
• Machine/deep learning frameworks (models, training, pipeline optimization, deployment in the cloud/at the edge (OpenShift), monitoring workloads with Prometheus and Grafana)
• Performance optimization for low latency/resilience using adaptive ML/DL/RL models for customer IoT data
• Analysis of large sensor data sets with Apache Spark, Kafka clusters
• Kasten K10 data management platform on Kubernetes multi-cluster with Helm chart, deployment, backup/disaster recovery (RTO/RPO), data lifecycle and security management
• Implementation of multilayer artificial neural network (ANN) with TensorFlow 2 and Colab for regression and classification; data analysis and provisioning for applications; development of models for testing and training, deployment of models
• Automation of business streamline processes with AI (Azure OpenAI, Discord bots/Zapier apps AI assistants (IntelliJ, GitHub Copilot))