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Hen Heang

Engineering portfolio

Hen Heang

Backend-focused Software Engineer

Building reliable Java and Spring Boot systems with modern web technologies.

I develop enterprise APIs, database-driven applications and AI-enabled products using Spring Boot, PostgreSQL, MyBatis and Next.js.

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

All technologies

27 skills across 4 categories, shown as a compact icon-only carousel. Hover or focus an icon to see its technology name.

27 skills across 4 categories

Auto-scroll · Motion

AIAI-assisted development with Claude Code and Codex, with product integrations using OpenAI and Gemini.

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 available

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 available

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

Authentication · Multi-factor auth · RBAC

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

Source available

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

    Full-Stack Developer

    Bizplay · Seoul, South Korea

    Building enterprise financial applications for government and corporate clients in a Korean development environment, across Java services, Oracle data, and production web interfaces.

    • Building Java and MyBatis services backed by Oracle
    • Developing and maintaining enterprise web interfaces with JavaScript and jQuery
    • Java
    • MyBatis
    • SQL

  2. January 2024 — October 2025

    Software Engineer

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

    Built B2B billing and commerce systems from PostgreSQL schema design through secured Spring Boot APIs and supporting web interfaces.

    • Built B2B billing and payment features for enterprise clients
    • Designed PostgreSQL schemas and optimized SQL queries
    • 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. I specialize in Java, Spring Boot, MyBatis and PostgreSQL, with frontend experience using Next.js and TypeScript.

My professional work focuses on enterprise systems, API development and database-driven applications. I also build practical products in real estate, personal finance and AI-assisted learning.

I care about maintainable architecture, clear business logic 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