Java Backend Engineer - FinTech

IO Tech Solutions Limited; Hong Kong; On-site; HKD 900,000 - 1,200,000; Full time

Job summary

IO Tech Solutions Limited is seeking a Senior Java Backend Engineer to design, build, and optimize scalable distributed systems. The role focuses on Spring Boot microservices and high-throughput Apache Kafka data streaming, with emphasis on robust APIs, data pipelines, and reliable backend services.

You will work on real-time data processing, database optimization (PostgreSQL/MySQL/MongoDB), and caching strategies, while embracing CI/CD, Docker, and Kubernetes for deployment and reliability.

Qualifications

• Minimum 5 years of hands-on backend Java experience in enterprise systems.
• Deep expertise in the Spring ecosystem (Spring Boot, Spring Data JPA, Spring Security, Spring Cloud).
• Proven track record implementing event-driven architectures with Apache Kafka and related components.
• Strong knowledge of Microservices patterns (Circuit Breakers, CQRS, Event Sourcing, API Gateways).
• SQL optimization and ORM frameworks like Hibernate; NoSQL familiarity (MongoDB).
• Cloud familiarity (AWS, GCP or Azure); Docker and CI/CD tools like Jenkins, GitHub Actions.

Responsibilities

• Design and develop low-latency, high-availability microservices using Spring Boot.
• Build, maintain, and optimize real-time data streaming pipelines with Apache Kafka.
• Design secure RESTful APIs and handle service-to-service communication via gRPC or asynchronous messaging.
• Implement data persistence with PostgreSQL, MySQL and MongoDB, focusing on performance and indexing.
• Integrate distributed caching like Redis to improve responsiveness and scale.
• Write clean, maintainable code with automated testing (JUnit, Mockito) and integration tests.
• Containerize applications with Docker and deploy on Kubernetes with CI/CD pipelines.

Skills

Java

Spring Boot

Microservices

Kafka

REST APIs

SQL optimization

NoSQL

Caching

CI/CD

JUnit Mockito

Tools

Docker

Kubernetes

PostgreSQL

MySQL

MongoDB

Hibernate

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).

PerformancePerformance TuningSpring SecurityFinTechSpringCI/CD pipelinesDistributed SystemsDataMessagingJPACloudAPIDatabaseMockitoRESTful APIsDevelopmentPipelinesApache KafkaGithub ActionsKafkaGcpApacheNoSQLSourcingHibernateJUnitCI/CDAzureSoftware DevelopmentRedisArchitectureReliabilityMicroservicesOptimizationSpring BootInfrastructureIntegrationAWSKubernetesJenkinsDatabasesGithubSecurityPostgreSQLMongoDBDockerSoftwareTestingMySQLDesignJavaSQLCommunication