Sr Java Developer

We are hiring a Senior Java Developer for a contract position (6+ months) based in Walnut Creek, California. You will lead technical direction and delivery for a large multi-module Java enterprise platform featuring a modern React UI, batch processing, partner integrations, and AWS-hosted containerized deployments. In this role, you will own design and architecture decisions across a mature codebase while modernizing the platform's architecture, cloud operations, and developer experience.

Responsibilities

• Lead end-to-end delivery of features across backend services, APIs, UI, and integrations
• Architect and review solutions in a large Maven multi-module Java/Spring application
• Guide evolution of the platform, balancing legacy server-rendered UI alongside modern React, APIs, and batch jobs
• Own or partner on AWS deployment and reliability for containerized Tomcat services, including ECS, CDK pipelines, secrets management, and observability
• Mentor engineers, set coding standards, drive design reviews, and improve CI/CD and release quality
• Partner with product and stakeholders on external integrations
• Diagnose production issues across application, database, and infrastructure layers; strengthen monitoring and runbooks
• Optionally lead or contribute to AI-agent initiatives that automate workflows, data handling, or developer productivity

Qualifications

• Required

• 8+ years of professional software engineering experience, with 2+ years in a lead, staff, or tech-lead capacity

• Deep expertise in Java (Java 8 or later) and comfort working with large enterprise codebases

• Strong hands-on experience with Spring (MVC, Security, Batch, SOAP/REST), Hibernate/JPA, and relational data modeling

• Solid SQL and MySQL skills, including schema design, query tuning, and transactional integrity

• Experience with Maven, multi-module builds, and Tomcat or similar Java application servers

• Proven production AWS experience, ideally with ECS/Fargate, ECR, ALB, Secrets Manager/SSM, S3, CloudWatch, and Infrastructure as Code (CDK, CloudFormation, or Terraform)

• Experience modernizing or maintaining legacy enterprise systems while delivering incremental improvements safely

• Strong design, debugging, and communication skills; ability to lead without blocking the team

• Preferred

• React or similar single-page application experience (Vite, Redux/RTK, Material UI)

• Observability experience with Datadog, structured logging, APM, and on-call practices

• Docker, CI/CD (Jenkins, CodePipeline/CodeBuild), and artifact registries (CodeArtifact/Nexus)

• AI agent building experience, including tool-calling agents, MCP, or workflow automation agents applied to enterprise systems