Thanh N.

Senior Java / Spring Boot developer with 1,000+ Upwork hours, 37 completed projects, a 100% Job Success Score, and a 4.9/5 client rating. I specialize in backend development, REST APIs, API integrations, and maintaining or extending existing Java/Spring applications. One of my long-term Upwork engagements has lasted 4+ years and 850+ hours, supporting and developing a Java open-source project. I’m comfortable working with existing codebases, understanding unfamiliar systems, fixing bugs, adding features, and delivering maintainable solutions without unnecessary rewrites. What I can help you with: • Java / Spring Boot backend development • REST API design and development • Spring MVC / Spring Framework • Hibernate / JPA and SQL • Third-party API integrations • Backend bug fixing and troubleshooting • Existing codebase maintenance and feature development • Refactoring and improving legacy Java applications • Unit testing with JUnit • Node.js backend development • React when full-stack work is required I’m particularly comfortable with projects where you already have an application and need an experienced developer to understand the codebase, fix issues, implement new features, or continue development. I value clear communication, clean code, practical solutions, and long-term collaboration. If you have an existing Java/Spring project that needs development or maintenance, send me the details and I’ll take a look.