Open to inquiries — just askTristan Rücker
Fullstack Developer — Java & React
As a "fullstack software developer" I'm working mainly with the technologies Java/Spring/Hibernate in the backend and React in the frontend. I started with the implementation of backend code in my really early days and worked my way also into the frontend, which I now master just as well. Overall, I am a very versatile software developer with a broad knowledge in different technologies such as Vue.js, Angular, Kubernetes. For more see my skills section.
What I work with
- Java
- Spring Boot
- React
- Vue.js
- Angular
- JavaScript/TypeScript
- Python
- ES6
- SCSS
- Docker
- Kubernetes
- and many others
Projects I've worked on
05/2025 – todayREWEFull Stack DeveloperModernising and re-thinking applications in a critical infrastructure (KRITIS) environment (project NEO)
- Fulfilling and implementing ISO 27001 requirements
- Backend development with Java/Spring
- Heavy use of Kafka (dead-letter topics, Schema Registry, JSON Schema/Avro), storing and using master data via log compaction, handling the ordering of incoming events
- Many microservices
- Architecture documentation with arc42
- Feature toggles
- Extensive use of Grafana (metrics, logs, alerts)
- Frontend development with Angular
- Working with LLMs, MCP servers and AGENTS.md (first GitHub Copilot, later Claude Code)
- Migrating data from the legacy world to the new platform
- Working with Rancher and the new REWE Tech Platform (ArgoCD etc.)
- API testing with ReadyAPI
- Started the migration to a new platform (RTP)
- Provisioning Google Cloud resources and roles with Terraform
2023 – todayCore Innovation GmbHCloud / Full Stack DeveloperApplication that presents financial data of large US listed companies in a clear and detailed way
- Automated AI extraction of text from PDF files using LLMs
- Frontend development with Next.js, React, Redux, Bootstrap, Axios
- SEO
- Working with LLMs, AGENTS.md, skills and Claude Code
- Backend development with Java/Spring
- Kubernetes cluster on Google Cloud (GKE)
- Automated build and deployment with GitHub Actions and Helm charts
- PostgreSQL inside the cluster with the CloudNativePG operator
- Taints and node affinity for workload placement
- Connection pooling with PgBouncer
- Automated PostgreSQL backups to Google Cloud Storage buckets
- Read/write splitting in the Java application: writes go to the primary, reads to the replicas
- Google Workload Identity
- Terraform
2023 – todayDXC Technology Deutschland GmbHSeminar TrainerJava seminars and workshops for apprentices
03/2021 – 2024Mercedes-Benz / Daimler Truck AGFull Stack DeveloperDevelopment and maintenance of the Mercedes-Benz GDPR application and around ten further applications
- Editing and extending BPMN diagrams (Camunda) and developing a business process platform based on Camunda
- Frontend development with Angular
- GDPR: frontend development with Vue.js, embedded into Adobe Experience Manager via the "Seamless" framework
- Backend development with Java/Spring
- Migrating GitLab CI pipelines to declarative Jenkins pipelines, later Jenkins to GitHub Actions
- Designing a Kubernetes cluster architecture for multiple applications in a private cloud
- Implementing that architecture (Ingress, Deployments, StatefulSets, Secrets, ClusterIP services, persistent volumes, NAS integration, RBAC)
- Rollout to DEV/INT/PROD with Helm, customising and installing Helm charts
- Kafka integration, data exchange and interface specification with AsyncAPI
- Kafka producers and consumers with Avro schemas, ACL management with Lenses.io
- Integrating Black Duck
- Migrating an application from Angular 8 to Angular 19
- Shipping Java logs to OpenSearch with Fluentd
- Generating complex PDF documents
- Keycloak integration with custom mappers (user federation) and an external identity provider
- Monitoring the Kubernetes cluster with Grafana/Prometheus
08/2020 – 03/2021Cologne Broadcasting Center GmbH (RTL)Full Stack DeveloperBuilding and integrating a middleware with Apollo and GraphQL
- Frontend development with React/Redux
- Unit tests with Jest, E2E tests with Cypress
- Identity management with Azure AD/Keycloak
- Backend development (microservices) with Java/Spring
11/2018 – 04/2020DERMALOG Identification Systems GmbHFull Stack DeveloperImplementing requirements for the Asian market and for Interpol
- Setting up an identity management solution (OAuth2 with JWT, stateless authentication)
- Designing various REST interfaces
- Unit and integration tests
- Zero-downtime deployment scripts (rolling update) in Python
- Linux server configuration
- Implementing an offline mode (Vue.js)
- Implementing the ANSI/NIST-ITL standard
09/2018 – 10/2018COYO GmbHFull Stack DeveloperFrontend development with Angular, Protractor and Jasmine
- Elasticsearch search optimisation
- Started splitting a monolith into microservices (Java, Spring, Docker)
- Database model changes (Flyway, PostgreSQL)
06/2018 – 08/2018S-KON eKontor GmbHFrontend DeveloperSetting up a greenfield frontend environment
- Implementing requirements with Vue.js, JavaScript and TypeScript
- Coordinating with a UX/UI team (Zeplin)
- Building a pattern library and designing components
- Unit and E2E tests (Jest, Cypress)
01/2018 – 06/2018Telefónica Deutschland Holding AGFull Stack DeveloperRapid prototyping of many different applications (Java, Spring, Hibernate)
- Migrating applications to Spring Boot 2
- Unit and integration tests (Spring MockMvc, JUnit, Mockito)
- Database model changes (Oracle DB, Flyway)
- Frontend development with Vue.js and design changes (Bootstrap, Bulma, SCSS)
- Error monitoring with Sentry
- Integrating a payment service (SOAP, Apache CXF)
- CI/CD pipelines for Jenkins
- Estimating user stories in an 8-person Scrum team
07/2017 – 12/2018Self-employedAndroid DeveloperTravel journal app for Android with 10,000+ downloads on Google Play
- Dependency injection with Dagger 2
- Google Location API, Google Places API, Retrofit, RxJava
- Improving usability with Firebase Analytics
- Automatic backups via the Google Drive API
- SQLite database design and migrations
- Tests with JUnit, Mockito and Espresso
03/2017 – 12/2017DB Systel GmbHAndroid DeveloperFurther development of a mobile terminal for train conductors (Android)
- Implementing technical components, interfaces and modules across interconnected APKs according to customer standards
- Changing the database architecture (SQLite)
- Technical documentation of the components
- Tests with JUnit and Mockito, UI tests with UI Automator and Robolectric
- Working in a large interdisciplinary team
02/2016 – 02/2017HZDBackend DeveloperFurther development of administration software for housing benefit recipients (Java, Hibernate, SWT)
- Implementing address data auto-completion
- Database model changes (Oracle DB, PL/SQL, Flyway)
- Reviewing the application for vulnerabilities (SQL injection)
- Test cases with Selenium
- Breaking stories down into tasks and estimating in a 6-person Scrum team
02/2016 – 02/2017HZDFull Stack DeveloperFurther development of the central protection document register of the Hessian state administration (C#, Razor, Entity Framework)
- Bug fixing
- Database model changes (Oracle DB)
07/2015 – 01/2016CSC Deutschland GmbHFull Stack DeveloperAutomated billing system for a private cloud
- Test-driven development with Java, Spring and Hibernate
- Generating invoices as PDF or Excel files for download
- Frontend work with JSF, ICEfaces, PrimeFaces, jQuery and Bootstrap
- MySQL schema changes with Liquibase
03/2015 – 06/2015CSC Deutschland GmbHSoftware DeveloperSurvey application for rating seminar trainers (Java, Spring, Hibernate, Thymeleaf)
- Developing a content management system (CMS)
- Designing the MySQL database architecture
- Frontend with HTML5, CSS3, Bootstrap, Thymeleaf and jQuery
