Freelance Senior Java Backend Engineer | Java 21 | Spring Framework
Job Title: Senior Java Backend Engineer
Job Type: Part-Time | Freelance
Location: Remote
Experience: 5+ Years
About the Role
We are looking for a Senior Java Backend Engineer with strong hands-on experience in modern Java backend development, REST APIs, database integration, and enterprise system integrations.
The ideal candidate should be comfortable working with Java 21, Spring Framework 6, Jersey/JAX-RS, Jakarta EE, Couchbase, and both REST and SOAP-based integrations.
This is a part-time remote opportunity suitable for an engineer who can independently develop, troubleshoot, test, and maintain production-grade backend services.
Key Responsibilities
- Develop and maintain backend services using Java 21 and Spring Framework 6.
- Build REST APIs using Jersey/JAX-RS and Jakarta EE/Servlet APIs.
- Work with Couchbase for data persistence and database operations.
- Implement JSON serialization/deserialization using Jackson.
- Develop and maintain SOAP integrations using Apache CXF, WSDL, JAXB, and SOAP.
- Integrate with downstream services such as EOS, SmartSwipe, and Communications Preference services using REST clients.
- Develop scalable and maintainable Maven multi-module applications.
- Implement application logging and distributed tracing using Log4j 2 and OpenTelemetry.
- Write and maintain unit/integration tests using JUnit 4, PowerMock, and EasyMock.
- Maintain code quality using JaCoCo, SonarQube, PMD, and Checkstyle.
- Deploy Java applications as WAR files to Tomcat/application servers.
- Work with Jenkins for CI/CD automation.
- Support containerized deployments using Docker/Kubernetes and Helm.
- Troubleshoot production issues and contribute to performance, reliability, and code-quality improvements.
Required Skills
- Strong hands-on experience with Java 21
- Spring Framework 6
- Jersey / JAX-RS
- Jakarta EE / Servlet APIs
- Couchbase
- Maven / Multi-module Maven projects
- Jackson
- REST API development and REST client integrations
- Apache CXF / SOAP / WSDL / JAXB
- JUnit 4 / PowerMock / EasyMock
- Jenkins CI/CD
- Kubernetes / Helm
- Tomcat / Application Server deployment
- Log4j 2 and OpenTelemetry
- SonarQube, JaCoCo, PMD, Checkstyle
Good to Have
- Experience working with enterprise-scale Java applications
- Experience integrating multiple downstream services
- Experience troubleshooting distributed systems
- Experience with cloud/containerized deployments
- Strong understanding of API design, testing, observability, and production support
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