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[Senior Backend Engineer // Java & Distributed Systems]

More freedom.More love.A good lifefor everyone.

Discover what's beautiful. Create something meaningful. Share it with the world.

I am a Java-first backend engineer with 8+ years of experience, including 5+ years delivering full-stack applications with Java, Spring Boot, and React. My core strength is turning complex business processes into reliable APIs, domain models, and distributed workflows. My full-stack, platform, and DevOps experience lets me take those systems from product requirements through production and operate them at scale.

View selected workVisit Physica
8+Years of Java engineering
5+Years full-stack with React + Java
10KSuppliers connected
4K+Enterprise users served
Chapter 01 / Selected backend work

[Selected case files // Java systems in production]

Backend engineering for real operational complexity.

CASE-001

Java CI/CD Orchestration Backend // OKX

OKone

Built Java and Spring Boot backend services for OKone's CI/CD orchestration and artifact-management domains, turning complex delivery rules into reliable APIs and production workflows.

Designed the orchestration domain model and execution layer above GitLab CI/CD, supporting multi-stage workflows, task dependencies, conditional execution, pipeline triggering, state tracking, and runtime monitoring.

  • 1,000+ engineers
  • 10K+ builds / day
  • 20+ templates
  • 50%+ runtime reduction
  • Java
  • Spring Boot
  • Spring Cloud
  • Nacos
  • MyBatis
  • GitLab CI/CD
  • Kubernetes
  • SonarQube
CASE-002

Java AI Workflow Orchestration // OKX

Oli

Designed a DAG-based orchestration engine for complex AI-agent workflows, with task dependencies, parallel execution, conditional routing, retries, timeouts, and failure recovery.

Implemented the backend integrations, MCP servers, and reusable agent skills that let agents inspect code-quality results and trigger or monitor engineering workflows.

  • 1,000+ users
  • 60% shorter development cycles
  • Java
  • Spring Boot
  • DAG Orchestration
  • MCP Servers
  • Agent Skills
CASE-003

Enterprise ERP & Supplier Platform // Hung Hing

Enterprise Systems

Developed Java and Spring Boot backend services for an enterprise ERP spanning more than 20 business modules, then led the delivery of a supplier platform coordinating procurement with more than 10,000 suppliers.

Owned backend implementation, data integration, and supporting React features across the systems. I also introduced GitLab, Docker, reusable CI/CD pipelines, and ELK logging to make those applications easier to ship and operate.

  • 4,000+ users
  • 20+ business modules
  • 10,000 suppliers
  • 60% faster deployment
  • Java
  • Spring Boot
  • React
  • Docker
  • GitLab CI/CD
  • ELK
  • Bash
Chapter 02 / Independent product
PRODUCT-001Live / 500+ early users

[AI health // Independently built with AI]

Physica Health

From an idea to real users - independently designed, built, and shipped with AI.

Physica is an AI health companion that turns habit change into a personalized narrative journey. I independently owned product strategy, UX, system architecture, full-stack development, and production deployment, while designing and iteratively optimizing its agent experience through prompt engineering, RAG, MCP integration, response evaluation, and safety guardrails.

Visit live product

[What I owned]

  • Product strategy & positioning
  • Product & UX design
  • System architecture & full-stack development
  • Agent, RAG & MCP integration
  • Evaluation, safety & iteration
500+ early usersSolo product ownershipLive in production
Chapter 03 / Capabilities

[Field notes // How I create leverage]

Capabilities backed by shipped work.

    01

    Backend & Distributed Systems

    Java backend services and distributed architectures across fintech, enterprise ERP, supplier systems, and developer platforms, backed by 5+ years of end-to-end delivery with React and Java.

    8+ years Java · 5+ years React + Java full-stack delivery
    • Java 8/17
    • Spring Boot
    • Spring MVC
    • Spring Cloud
    • REST APIs
    • Microservices
    • MyBatis
    • Nacos
    • Kafka
    • Redis
    • React
    02

    Workflow & Domain Engineering

    Complex business workflows modeled as maintainable services: dependency graphs, conditional routing, lifecycle state, failure recovery, data integration, and production observability.

    OKone · 10K+ daily workflows · 50%+ runtime reduction / ERP · 20+ modules
    • Domain Modeling
    • DAG Orchestration
    • State Machines
    • SQL
    • Kafka
    • Observability
    03

    AI Agent Backends

    Backend infrastructure for agentic applications, including DAG execution, parallel tasks, retries, timeouts, MCP servers, tool integration, and safety-aware product workflows.

    Oli · 1,000+ users · 60% shorter development cycles / Physica · 500+ early users
    • Java
    • Spring Boot
    • MCP
    • RAG
    • Agent Skills
    • Tool Integration
    04

    Production Delivery

    End-to-end ownership from requirements and system design through implementation, testing, deployment, observability, and feedback-driven iteration.

    Backend engineering first, with the delivery skills to run what I build in production
    • System Design
    • Testing
    • GitLab CI/CD
    • Docker
    • Kubernetes
    • ELK
    • Production Rollout
[Index // Full toolkit]Full technology index+ Expand− Close
Backend & APIs

Java 8/17 · Spring Boot · Spring MVC · Spring Cloud · Go · Python · REST APIs · Microservices · MyBatis · Nacos

Data, Messaging & Quality

MySQL · PostgreSQL (Neon) · MongoDB · Oracle · SQL Optimization · Kafka · Redis · TDD · JMeter · JasperReports · Pentaho

Agent Engineering · Oli

DAG Orchestration · MCP Servers · Agent Skills · Tool Integration

Applied AI Product · Physica

Agent Design · Prompt Engineering · RAG · Context Management · MCP Integration · Response Evaluation · Safety Guardrails

Platform & Delivery

GitLab CI/CD · Kubernetes · Docker · Helm · Argo CD · Artifact Management · SonarQube · Prometheus · Grafana · ELK · Linux · Bash

Full-Stack Delivery & Product

React · Next.js · TypeScript · JavaScript · HTML/CSS · Product Discovery · PRDs · UX · AI-assisted Prototyping

Chapter 04 / Career journey

[Work log // 2016-2026]

From the systems up.

01

OKX

Senior Engineer (DevSecOps) · S-rated / Top 5%

Java Backend · Distributed Workflows · AI Agent Systems
02

Hung Hing Printing Group

Senior Analyst Programmer · Two stints

Java Backend · ERP · Supplier Systems
03

Automated Systems (H.K.)

Analyst Programmer

Java Enterprise Systems · Reporting · Data Migration