Senior Fullstack-Developer (Java/Spring-Boot/Kubernetes/Azure/AWS/Kafka/ReactJS)

Hey, I am Sebastian! I am working since 2014 in Java projects and gained a lot of expiriences in Spring Boot Microservices, Apache Kafka, Kubernetes, AWS & Azure Cloud as well as ReactJS as frontend technology.

In the backend, I have extensive experience developing Spring Boot services, focusing on implementing robust, scalable and secured backend components. On the frontend side, I work closely with ReactJS for several years to create modern and user-friendly interfaces.

As database technologies, I mostly worked with PostgreSQL, Oracle, and MySQL databases. For database migrations, I often used Flyway (for several databases) in Spring Boot projects. In my last project, we migrated a very large table, from a Oracle on-premise database to a PostgreSQL database in the Azure Cloud. We had to face different questions like how to migrate such big data, how to do backups and restoring in case of an incident, how to partition the table.

Besides communication via REST (+ OpenAPI), I have been working with message broker technologies, especially Apache Kafka, for many years. In various projects, I have implemented traditional consumer functionalities, and in my recent project, I successfully processed live data (approximately 600.000 events per minute) using Kafka Streams and Kafka Connect. Additionally, I have practical experience with JMS and Azure EventHub.

Ensuring a robust test coverage and adhering to "Clean Code" principles (e.g. utilizing SonarQube) is a standard practice for me. Beyond traditional unit and integration tests within the Java project, I have expertise in end-to-end testing using Cypress (with real backend or mock), as well as using tools such as Applitools (for browser screenshot tests) or LambdaTest/Browserstack (for manual tests). Of cause, I perform tests at various environments.

In addition to development, deployment (via GitLab CI or Jenkins) across different stages is an central aspect of my daily work. In my last project, I've gained substantial experience in migrating Java Spring Boot services from on-premise world to the Azure Kubernetes Cloud. Additionally, I really love to work with AWS products, including S3, SES, SNS, RDS, VPC, CloudFront, IAM, Route53, configuring them through CloudFormation (Infrastructure-as-Code).

For error diagnosis and server/service monitoring, I integrate Kibana (ELK-Stack) / Loki for logging, OpenTelemetry for tracing, and Grafana (with Prometheus and AWS CloudWatch) for monitoring, along with configured alerting through OpsGenie, Microsoft Teams Channel, Slack & Email.

I typically engage in projects organized with agility and SCRUM methodology, leveraging the Atlassian cloud service Jira for release and sprint planning. My favorite IDE is IntelliJ. The default project language was English in all my last projects.

Could I be a suitable match for your project? I would love to get an invitation for a technical interview and have a deep dive how I can support your team.