NGUYỄN QUANG SANG

Project: Superbit (Crypto-Integrated Platform)

Description:

A large-scale multi-tenant built on Spring Boot, following a modular monolithic architecture.
The system is packaged into multiple executable modules (Portal, Back Office, Job Processor, Callback Service), with tenant isolation at the database schema level.

Responsibilities:
Designed to support high concurrency, high traffic workloads, and complex business workflows.

• Design & Architecture: Designed and implemented a Modular Monolithic architecture with a Multi-tenant model (Schema-level isolation), ensuring data security and seamless scalability for multiple enterprise clients.
• High-Throughput Callback System: Leveraged AWS Auto Scaling Groups to dynamically adjust resources based on real-time traffic. Integrated RabbitMQ as a "shock absorber" to handle traffic spikes, while optimizing Java API latency to under 100ms for mission-critical transactions.
• System Optimization: Enhanced application responsiveness by implementing a Multi-tier Caching strategy (Redis & Caffeine) and resolved data contention/concurrency issues using Distributed Locking.
• Query Optimization: Optimized complex SQL queries and indexing, reducing big data report generation time from minutes to seconds.
• Leadership & Mentoring: Led and mentored a sub-team of 5 engineers, review code and established knowledge-sharing sessions.

Technologies:
- Languages & Frameworks: Java 21, Spring Boot 3.x
- Messaging & Streaming: RabbitMQ
- Caching: Redis, Local Cache (Caffeine)
- Database: MySQL
- Cloud & Infrastructure: AWS
- Logging & Observability: Fluent Bit, Script server

Project: Payment Gateway & Card Management System

Description:
A core financial platform for a Singapore-based Fintech, providing end-to-end Card Life-cycle Management and Payment Gateway solutions for Australia and Cambodia markets.

Key flows:

• Off-us: Payment Gateway → Acquiring Bank → Card Scheme → Issuing Bank
• On-us: Payment Gateway → Acquiring Bank → Issuing Bank

Responsibilities:

• Legacy System Migration: Played a pivotal role in modernizing the core system by successfully migrating legacy Struts v1 and Servlet-based components to a high-performance Spring Boot microservices architecture.
• Frontend Modernization: Collaborated on transitioning the user interface from traditional server-side rendering to a modern, responsive ReactJS Single-Page Application (SPA), improving user experience and system modularity.
• API Design & Integration: Designed and optimized secure RESTful APIs to facilitate seamless communication between the card management core and third-party payment providers, ensuring data integrity and security.
• Deployment & Environment Management: Directly supported and managed system deployments across SIT (System Integration Testing) and UAT (User Acceptance Testing) environments.

Technologies:
Java (Spring Boot 3.2, Struts v1, Servlet), Oracle Database, MySQL, Next.js

Project: Insurance Management System (France)

• Developed backend services using Java Spring Boot for insurance workflows.
• Designed and optimized MySQL queries for business reports.
• Built frontend features using ReactJS.

Project: IoT Smart Home Platform (Singapore)

• Developed backend APIs for device management and monitoring.
• Built frontend interfaces using Next.js.
• Worked with PostgreSQL for device and user data management.

Technologies:
Java Spring Boot, ReactJS, Next.js, MySQL, PostgreSQL

Project: Financial Management System (Mobifone – Southern Region, Vietnam)

Description:
A financial management system supporting accounting and financial operations for Mobifone’s southern region.

Responsibilities:

• Maintained and enhanced backend services using Java Spring Boot.
• Analyzed and fixed backend issues related to financial business logic.
• Worked with Oracle Database to handle financial data and improve query correctness.
• Collaborated with team members to investigate issues and ensure system stability.

Technologies:
Java Spring Boot, Oracle Database, Hibernate, Git, Maven
Frontend: Angular

• Java Intern – BPC Banking Technologies: Gained foundational experience in Java (EJB), Oracle SQL, and JSF. Assisted in bug fixing and maintaining modules for SmartVista banking platform and internal management systems.
• Java Intern – Ban Vien Company: embedded systems and IoT