Senior Backend Java Developer - API & Spring Expert

Optimum Solutions (Singapore) Pte Ltd.; Singapore; On-site; SGD 90,000 - 140,000; Full time

Job summary

Optimum Solutions (Singapore) Pte Ltd. is seeking an experienced Backend Java Developer to design, build, and maintain high-throughput RESTful APIs and enterprise backend components.

You will focus on scalable code, multi-database interactions, asynchronous execution, and strong object-oriented and functional programming across the stack. The role emphasizes REST API design with Java 11+/Spring Boot, SOLID patterns, and OpenAPI documentation, plus tuning data persistence via Spring Data

Qualifications

• 5+ years of hands-on software development with Java 11/17+
• Expertise in Spring Boot, Spring Core, Spring MVC
• Strong REST API design, HTTP status codes, JSON processing
• Proficient in Spring Data JPA/Hibernate and multi-datasource routing
• Experience with Kafka or RabbitMQ
• Knowledge of design patterns, TDD (JUnit 5, Mockito), and build tools (Maven/Gradle)

Responsibilities

• Design, build, and maintain RESTful APIs and backend services using Java 11+ and Spring Boot.
• Apply SOLID principles and reusable module design across services.
• Document REST endpoints with OpenAPI/Swagger.
• Utilize concurrency utilities and asynchronous patterns for performance.
• Diagnose memory issues and optimize with profiling tools.
• Design relational and NoSQL schemas and manage data persistence with Spring Data JPA/Hibernate.
• Write optimized SQL, indexing, and manage connections and caching (Redis).
• Implement security with OAuth2/JWT, logging, health checks, and metrics.
• Write clean, modular, and tested code using JUnit/Mockito.
• Participate in code reviews and maintain test coverage.

Skills

Java 11/17+

Spring Boot

REST APIs

Multithreading

JUnit/Mockito

SQL/NoSQL Databases

Kafka/RabbitMQ

Tools

Maven/Gradle

Flyway/Liquibase

Hibernate

Spring Data JPA

Redis

Docker

Job description

Optimum Solutions (Singapore) Pte Ltd. is seeking an experienced Backend Java Developer to design, build, and maintain high-throughput RESTful APIs and enterprise backend components.

You will focus on scalable code, multi-database interactions, asynchronous execution, and strong object-oriented and functional programming across the stack. The role emphasizes REST API design with Java 11+/Spring Boot, SOLID patterns, and OpenAPI documentation, plus tuning data persistence via Spring Data