Contract Senior Software Engineer (Java Spring)

About the role

As a contract Senior Software Engineer, you will design and deliver Java Spring‑based loyalty engine services and RESTful APIs for world‑class clients, collaborate daily with engineers and product teams, influence product roadmaps, and provide consultative expertise across architecture, integration, and security while mentoring others.

About the company

Stable Kernel is a privately held technology services firm and custom software developer headquartered in Atlanta, GA. It builds scalable software solutions for innovative enterprises, has a 10‑plus‑year growth trajectory, is Great Place to Work Certified, and promotes an inclusive, people‑first culture.

Requirements

• 6‑10 years of back‑end development experience, primarily Java
• Extensive experience serving as a trusted consultant to stakeholders and cross‑functional teams on backend service design, delivery, and integration
• Degree in Computer Science or related field or equivalent practical experience
• Proficiency with Java server‑side development and the Spring ecosystem (Spring Boot, MVC, Security, Data)
• Strong understanding of domain‑driven design principles and bounded contexts
• Experience designing RESTful APIs using contract‑first approaches and OpenAPI/Swagger
• Knowledge of event‑driven and message‑oriented patterns (Kafka, RabbitMQ, SQS)
• Familiarity with integration patterns such as API gateway, circuit breaker, retry/backoff, caching (Redis) and ETL/event‑based flows
• Experience with relational databases (PostgreSQL, MySQL), schema design, query optimization, and transactional integrity; NoSQL a plus
• Experience with CI/CD tooling (Jenkins, GitHub Actions) and pipeline authoring
• Containerization and orchestration experience (Docker, Kubernetes)
• Proficiency with Git source control
• Experience with observability tools (Datadog, Splunk, New Relic, OpenTelemetry)
• Automated testing skills across unit (JUnit, Mockito), integration, contract, and scenario‑based validation
• Experience with cloud platforms (AWS, GCP, Azure) and managed services (queues, caches, databases)
• Understanding of identity and access management protocols (OAuth 2.0, OIDC, SAML)
• Nice to have: experience building loyalty or rewards engines
• Nice to have: experience building BFF or API aggregation layers for mobile applications
• Nice to have: familiarity with Salesforce CRM, Commerce Cloud, or identity integration patterns
• Nice to have: experience with POS system integration and transaction‑level data processing
• Nice to have: background in fintech, payments, or audit‑critical financial systems
• Nice to have: experience modeling complex account hierarchies
• Nice to have: experience with feature flagging and progressive rollout
• Nice to have: experience collaborating with mobile teams on API contracts