Java Backend Engineer - FinTech

IO TECH SOLUTIONS LIMITED; Hong Kong; On-site; HKD 900,000 - 1,400,000; Full time

Job summary

IO TECH SOLUTIONS LIMITED is seeking a Senior Java Backend Engineer with 5+ years of experience to design, build, and optimize scalable backend systems in Hong Kong. You will focus on microservices using Spring Boot and high-throughput data streaming with Apache Kafka, creating robust APIs and ensuring system reliability.

Responsibilities include implementing data persistence across PostgreSQL/MySQL and MongoDB, integrating Redis caching, and delivering well-tested code within CI/CD pipelines

Qualifications

• 5+ years of backend Java development in enterprise environments.
• Deep Spring ecosystem knowledge (Boot, Data JPA, Security, Cloud).
• Experience building event-driven architectures with Kafka.
• Strong SQL and ORM performance tuning.

Responsibilities

• Design and build low-latency microservices with Spring Boot.
• Develop real-time data pipelines using Apache Kafka.
• Create secure RESTful APIs and service communication (gRPC).
• Optimize data persistence across relational and NoSQL stores.
• Implement caching with Redis/Memcached and ensure test coverage.

Skills

Java 11/17+

Spring Boot

Kafka

REST APIs

gRPC

SQL & ORM

MongoDB

Docker

Kubernetes

CI/CD

JUnit/Mockito

Tools

PostgreSQL

MySQL

MongoDB

Redis

Memcached

Apache Kafka

Docker

Kubernetes

Jenkins

GitHub Actions

Job description

We are seeking a highly skilled Senior Java Backend Engineer with over 5 years of professional software development experience. In this role, you will design, build, and optimize scalable, high-performance distributed systems. The ideal candidate possesses deep expertise in Spring Boot for microservices architecture and Apache Kafka for high-throughput, event-driven data streaming. You will be responsible for creating robust enterprise APIs, optimizing complex data pipelines, and ensuring the reliability of critical backend services.

• Design and develop low-latency, high-availability microservices using the Spring Boot framework.
• Build, maintain, and optimize real-time data streaming pipelines and messaging architectures utilizing Apache Kafka.
• Design clean, scalable, and secure RESTful APIs and handle service-to-service communication via gRPC or asynchronous messaging.
• Implement data persistence and complex queries across relational databases (e.g., PostgreSQL, MySQL) and NoSQL stores (e.g., MongoDB), focusing heavily on performance tuning and indexing.
• Integrate distributed caching solutions like Redis or Memcached to improve application responsiveness and scale.
• Write high-quality, maintainable code following clean-code principles. Drive rigorous automated testing practices, including unit (JUnit, Mockito) and integration tests.
• Containerize applications using Docker and collaborate on deployments within Kubernetes clusters managed via CI/CD pipelines.

Required Skills & Qualifications

• Minimum 5 years of hands-on professional backend software development using Java (Java 11/17+).
• Deep understanding of the Spring ecosystem (Spring Boot, Spring Data JPA, Spring Security, and Spring Cloud).
• Proven track record of implementing event-driven architectures with Apache Kafka, including knowledge of Kafka Topics, Partitions, Consumer Groups, Schema Registry, and Kafka Streams.
• Strong proficiency in Microservices patterns (Circuit Breakers via Resilience4j, CQRS, Event Sourcing, and API Gateways).
• Strong knowledge of SQL/PostgreSQL database optimization and ORM frameworks like Hibernate.
• Solid experience with cloud infrastructure (AWS, GCP, or Azure), Docker containers, and CI/CD tools (Jenkins, GitHub Actions).