Flexton Inc
Website:
flextoninc.com
Job details:
About the Role
We are looking for a Senior Java Backend Engineer to support the Spark → HubX migration at Prosper. You will take Low-Level Designs (LLDs) and independently implement backend features, working closely with onshore leads and offshore teammates on the same components and features. The ideal candidate is a hands-on engineer who combines deep Java and Spring Boot expertise with strong ownership, clear communication, and disciplined engineering practices.
Project Context
- Initiative: Migration and modernization of the Spark platform to HubX
- Timeline: Approximately 4 months
- Team: About 13 developers across onshore and offshore, with onshore leads driving design and direction
- Stack context: Java/Spring Boot microservices on the backend; the frontend is React. React is not a core requirement for this role, but a basic understanding of the end-to-end application flow is expected
Key Responsibilities
- Translate LLDs into production-quality Java/Spring Boot microservices and deliver features independently
- Build, integrate, and troubleshoot service-to-service interactions, including API contracts, data exchange, and failure handling
- Contribute to the migration of functionality and data flows from Spark to HubX, preserving behavior while modernizing implementation
- Write thorough unit and integration tests, and maintain high standards of code quality and maintainability
- Debug and resolve defects across services, using logs, metrics, and tracing to find root causes
- Review pull requests thoughtfully and incorporate feedback on your own PRs
- Use AI coding tools (e.g., Cursor) to work faster, while validating, testing, and being able to clearly explain every line of AI-generated code you submit
- Own your deliverables end to end, and raise blockers, risks, and dependencies early with onshore leads and teammates
- Collaborate daily with onshore and offshore engineers on shared components, keeping work aligned and avoiding rework
Required Technical Skills
Java and Spring Boot
- Very strong hands-on experience with Java (modern versions, 11+ preferred), including collections, concurrency, streams, exception handling, and memory/performance fundamentals
- Deep experience with Spring Boot and the Spring ecosystem: dependency injection, REST controllers, configuration and profiles, validation, exception handling, and Spring Data/JPA
- Solid object-oriented design, design patterns, and clean-code principles
Microservices and Service Interactions
- Proven experience designing and building microservices, including service boundaries, REST API design, and versioning
- Strong understanding of service-to-service communication: synchronous (REST) and, ideally, asynchronous messaging (e.g., Kafka, RabbitMQ, or similar)
- Familiarity with resilience patterns such as retries, timeouts, circuit breakers, idempotency, and handling partial failures
- Working knowledge of API security basics (e.g., OAuth2/JWT) and error and contract handling between services
Data and Persistence
- Strong SQL and relational database experience, including schema design, query tuning, and transactions
- Experience with ORM/JPA and an understanding of data consistency across services; exposure to NoSQL is a plus
Testing, Quality, and Debugging
- Strong unit testing practice (e.g., JUnit, Mockito) and experience with integration and API testing
- Ability to debug complex issues in distributed services using logs, metrics, and tracing
- Disciplined PR review habits: reviewing for correctness, readability, test coverage, and edge cases
Engineering Practices and AI-Assisted Development
- Comfortable with Git workflows, build tools (Maven/Gradle), and CI/CD pipelines
- Ability to read an LLD, ask the right clarifying questions, and implement independently
- Experience using AI coding tools such as Cursor is preferred. The candidate must be able to understand, validate, and clearly explain AI-generated code and PRs
Required Experience and Working Style
- 7-8+ years of backend software development experience
- Strong ownership and accountability: takes responsibility for deliverables and proactively communicates progress and blockers
- Clear written and verbal communication, suited to working with distributed onshore and offshore teams
- Self-driven and able to work with minimal supervision once the design is clear
Preferred Experience
- Migration or modernization experience: prior work moving legacy systems or platforms to a new architecture (highly preferred)
- Fintech or financial services: familiarity with financial-domain concerns such as data accuracy, auditability, and compliance
- Cloud experience: hands-on with AWS, Azure, or GCP, plus containerization (Docker/Kubernetes)
- Frontend awareness: basic understanding of how a React frontend interacts with backend APIs (no frontend development expected)
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