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Hen Heang

Engineering portfolio

Hen Heang

Backend / AX Software Engineer

Building reliable Java and Spring Boot systems while learning to make human + AI development workflows repeatable.

My foundation is backend engineering: enterprise APIs, business logic, and data-driven applications with Java, Spring Boot, MyBatis, PostgreSQL, and Oracle. I use AI-assisted development in practice and am building deeper understanding of Agent Harness, MCP, guardrails, and evaluations.

View Backend WorkView ResumeGitHub
2+ years experienceSeoul, South KoreaOpen to roles
Client
Spring Security + JWT
Spring Boot 3 REST API
MyBatis mappers
PostgreSQL + Flyway

H-Phsar request flow, from the client boundary to persistence.

Technical Skills

Engineering stack

Core technologies grouped by the work they support. Project-specific tools stay with the case studies where they were used.

Backend

Designing REST APIs and business logic with Spring Boot and Spring Security.

  • JavaVerified in project or professional experience data
  • Spring BootVerified in project or professional experience data
  • MyBatisVerified in project or professional experience data
  • Spring SecurityVerified in project or professional experience data
  • REST APIsVerified in project or professional experience data
Used inH-PhsarAuthHubDev Lab

Data

Modeling schemas and writing SQL across PostgreSQL and Oracle.

  • PostgreSQLVerified in project or professional experience data
  • OracleVerified in project or professional experience data
  • SQLVerified in project or professional experience data
  • JPA/FlywayVerified in project or professional experience data
Used inH-PhsarAuthHubDev Lab

Frontend Support

Extending backend work into Next.js clients when a product needs a frontend.

  • Next.jsVerified in project or professional experience data
  • TypeScriptVerified in project or professional experience data
  • JavaScript/jQueryVerified in project or professional experience data
Used inHengoMoney FlowKOSIGN

Delivery

Documenting APIs and shipping services with build tooling and CI pipelines.

  • Git/GitHub
  • Maven/GradleVerified in project or professional experience data
  • Docker/GitHub Actions
  • OpenAPI/Swagger
Used inDev Lab

Selected Work

Backend systems, explained end to end

A quick view of the problem, solution, and implementation—full architecture and trade-offs stay in each case study.

Backend API / Source

H-Phsar — B2B Marketplace API

architecture

Client
Spring Security + JWT
Spring Boot 3 REST API
MyBatis mappers
PostgreSQL + Flyway
Request path from the client boundary through the documented service and persistence layers.

Problem

Wholesale trade between distributors and retailers still runs on phone calls and paper: orders get lost, prices stay opaque, and neither side has a record of what was agreed.

Solution

A Spring Boot marketplace API connecting distributors and retailers through catalogs, carts, controlled order transitions, and real-time notifications.

My contribution

  • Separated role-specific APIs over one shared relational model
  • Enforced every order transition through an explicit state machine
  • Spring Boot 3
  • Java 17
  • MyBatis
View case studyGitHub

Backend API

Source

AuthHub — Reusable Authentication Service

A reusable Spring Boot authentication service with JWT refresh and revocation, MFA, RBAC, audit logging, and a sample secured API.

Role · Solo Developer — Backend

Engineering focus

Authentication · Multi-factor auth · RBAC

View case study
  • Spring Boot 3
  • Java 17
  • PostgreSQL
GitHub
Source

Dev Lab — Personal Practice & Tooling Monorepo

A structured monorepo for core Java exercises, Spring Boot practice, small backend applications, and engineering notes.

Role · Solo Developer

View case study
  • Spring Boot
  • Java 21
  • MyBatis
GitHub
Browse all projects

Experience

Professional Experience

Backend and full-stack roles in Korean enterprise teams — REST APIs, database-backed business logic, and production web applications.

  1. October 2025 — Present

    Backend Developer (Java & Spring Boot)

    Bizplay · Seoul, South Korea

    Building enterprise financial web applications for government agencies and corporate clients. Developing both frontend interfaces and backend API services in a Korean enterprise environment.

    • Developing frontend pages with HTML/CSS and JavaScript (jQuery)
    • Building backend services with Java and MyBatis
    • Java
    • MyBatis
    • Oracle

  2. January 2024 — October 2025

    Software Engineer

    KOSIGN [Korea Software Innovation Global Network] · Phnom Penh, Cambodia

    Developed B2B financial platforms including billing systems and e-commerce solutions. Built end-to-end features from database design to API implementation.

    • Built a B2B billing and payment platform for enterprise clients
    • Designed PostgreSQL database schemas and optimized query performance
    • Java 8+
    • Spring Boot
    • Spring Security
See the full career journey

About

Backend engineering, built on real business problems

I'm Hen Heang, a Cambodian software engineer currently working in South Korea. My primary foundation is backend engineering with Java, Spring Boot, MyBatis, PostgreSQL, and Oracle, supported by frontend delivery with Next.js and TypeScript.

My professional work focuses on enterprise systems, API development, and SQL-driven business logic. In personal projects, I have also integrated practical AI features and used Claude Code and Codex as development assistants.

I am growing toward Backend / AX Software Engineer through learning and practice in Agent Harness design, MCP, evaluations, DevOps, and system architecture. I care about maintainable systems, explicit decisions, verification, and software that solves real problems.

More about my background

Have a system to build?

I'm available for Java and Spring Boot backend roles, API work, and product teams that value dependable systems.

Start a conversationView Resume