Developer – Billing Systems (REF5676S)

Join a team responsible for one of the most business-critical areas within Deutsche Telekom's international group: billing systems. We deliver accurate, reliable, and flexibly configurable billing for fixed-line and mobile networks as well as mobile service providers — serving millions of customers.

We're actively working to merge fixed-line and mobile billing into a single, modern platform, while gradually retiring legacy systems. That means you won't be maintaining a static, "legacy-only" system — you'll be part of a continuously evolving architecture undergoing real modernization.

Your responsibilities will include:

• Developing and maintaining microservices (REST APIs and UI components)
• UI development using the Vaadin (Java) framework
• Writing automated tests (JUnit, Cucumber/Gherkin, Robot Framework)
• Building and optimizing CI/CD pipelines in GitLab
• Deploying and running Docker containers on Kubernetes / OpenShift
• Ensuring reliable communication between services and integrations
• Writing custom scripts for database synchronization (MongoDB)
• Creating technical documentation and knowledge resources

• Experience with Java / Spring Boot backend development
• Familiarity with our tech stack: Java, Spring Boot, MongoDB, Oracle DB, Shell, Maven
• Experience with tools such as GitLab, Jira, Grafana, Kibana, VSCode / IntelliJ, MongoDB Compass, Postman (or equivalent), SQL Developer
• Business-level proficiency in English
• German is not required

• Work on a large-scale system modernization project within an international corporate environment
• A modern, cloud-native tech stack (Kubernetes/OpenShift)
• Production-grade, business-critical systems with real impact on customer experience
• A collaborative, agile team culture

* Please be informed that our remote working possibility is only available within Hungary due to European taxation regulation.