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I'm Doan Trung Kien, a Java Backend Engineer based in Vietnam. I build backend services and asynchronous workflows, with a focus on maintainable code, reliable APIs, and performance.
I work with Java, Spring Boot, and Vert.x, verify behavior through automated tests, and optimize services with Redis caching and SQL query tuning. My interests include distributed systems and event-driven architecture.
An authentication project that exchanges login credentials for a signed JWT. The code demonstrates Spring Security authentication and JWT generation, parsing, and validation.
Java 21 · Spring Boot · Spring Security · JWT
A portable collection of skills for Codex, Claude Code, and Kiro. Shared workflow guides and installation helpers make the collection reusable across agent environments.
Agent workflows · Markdown · Shell · PowerShell
Backend
Data & messaging
Delivery & testing
Full stack & engineering practices
| Area | Technologies & tools |
|---|---|
| Languages | Java 21 · Go |
| Backend & frameworks | Spring Boot · Spring Data · Vert.x · Jmix · Backbase |
| APIs & identity | REST APIs · OpenAPI · Keycloak |
| Testing | JUnit · Mockito · Integration tests |
| Data & caching | PostgreSQL · MySQL · Redis · Elasticsearch |
| Messaging & discovery | RabbitMQ · Apache Kafka · ActiveMQ · Eureka |
| Build & delivery | Maven · Git · GitLab · GitFlow · Jenkins · Argo CD |
| Containers & operations | Kubernetes · Rancher · k9s · Docker (Basic) |
| Observability & engineering insights | Grafana · LinearB |
| AI-assisted development | OpenAI Codex · Claude Code · Kiro · Prompt Engineering |
Engineering practices: Clean Architecture, SOLID principles, asynchronous processing, caching strategies, SQL pagination and query tuning, production troubleshooting, and log analysis.
Updated hourly · Timestamp in UTC · Commits and pull requests cover the last 12 months. GitHub scheduling and caching may delay updates.
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Open to collaboration, project discussions, and exchanging technical ideas.
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