Jason Choi · Full-Stack Software Developer

Three projects that show how I work.

Full-Stack Software Developer at Reflex Systems, Netherlands, since December 2024
Previously at Qualogy Caribbean
Fluent in Dutch and English

012022

Online Lottery Platform

One production platform running across three cloud providers, AWS, Tencent Cloud, and Alibaba Cloud, behind Cloudflare DNS. Built with React, Express, MariaDB, and Redis for an online lottery.

Three cloud providers managed as one production environment.
Content is delivered through CDN networks on several clouds.
Fast data access through Redis caching.

What I did

Built the frontend in React and the REST API in Express, served through Nginx.
Designed the data layer on MariaDB, with Redis for caching and in-memory data.
Managed DNS through Cloudflare.
Ran the platform across AWS, Tencent Cloud, and Alibaba Cloud, using cloud servers (EC2), object storage (S3), and CDN.

Stack

React.js
Express.js
MariaDB
Redis
Nginx
Cloudflare
Amazon EC2
Amazon S3
Tencent Cloud
Alibaba Cloud

Live demo· soonGitHub· soonArchitecture design· soon

022026

Attendance, Payroll & Employee Management

A web application that brings attendance, payroll, leave, and employee records into one system, with a self-service portal for employees and reports for administrators.

Attendance, leave, holidays, and payroll managed in one place.
Employees get their own portal for their information.
Reports export to PDF and Excel.
The interface is available in English, Spanish, and Chinese.

What I did

Built the frontend in React and TypeScript with Vite and HeroUI.
Built the REST API in Node.js and Express on MongoDB.
Implemented JWT sign-in, password hashing, and secure HTTP headers.
Added PDF and Excel generation, email sending, and file storage on Amazon S3.
Packaged the frontend and backend as Docker images in Amazon ECR and deployed them on Amazon ECS.

Stack

React.js
TypeScript
Vite
HeroUI
Node.js
Express.js
MongoDB
JWT
Amazon S3
Docker
Amazon ECR
Amazon ECS

Live demo· soonGitHub· soonArchitecture design· soon

03OngoingLearning lab

AWS Infrastructure as Code with Terraform

My own learning lab, where I build AWS infrastructure entirely with Terraform: CI/CD pipelines, EC2 servers, and S3 storage, all defined as code rather than set up by hand.

Every resource is created from Terraform code, with nothing configured by hand in the console.
Terraform state is stored safely, versioned, and locked against conflicting changes.
A monthly budget keeps AWS costs visible while I experiment.

What I did

Wrote a bootstrap module that creates the remote state bucket on Amazon S3.
Enabled versioning, KMS encryption, public access blocking, a bucket policy, and lifecycle rules on that bucket.
Configured an S3 backend with state locking for the dev environment.
Defined an AWS cost budget in Terraform.
Now building CI/CD pipelines, EC2 servers, and S3 storage, all from Terraform.

Stack

Terraform
Amazon Web Services (AWS)
Amazon EC2
Amazon S3
CI/CD

GitHub· soonArchitecture design· soon

Honorable mentions

ReferMe Marketplace
2025
A professional services marketplace that connects clients with trusted professionals for business and personal needs.
- Marketplace
- Web app
Visit site
ChatGroups
2024
AI chat rooms where people create songs and images live, share them instantly, and build communities around shared interests.
- Generative AI
- Communities
Visit site
AI Companion Chatbot
2024
An AI chatbot on Telegram that offers companionship through ongoing, personal conversations.
- Telegram
- LLM
School Management System
2025
A school management system for schools in Africa, including report cards, financial features, and a redesigned interface.
- Education
- Africa
ReferMe Marketplace
2025
A professional services marketplace that connects clients with trusted professionals for business and personal needs.
- Marketplace
- Web app
Visit site
ChatGroups
2024
AI chat rooms where people create songs and images live, share them instantly, and build communities around shared interests.
- Generative AI
- Communities
Visit site
AI Companion Chatbot
2024
An AI chatbot on Telegram that offers companionship through ongoing, personal conversations.
- Telegram
- LLM
School Management System
2025
A school management system for schools in Africa, including report cards, financial features, and a redesigned interface.
- Education
- Africa

Online Lottery Platform

One production platform running across three cloud providers, AWS, Tencent Cloud, and Alibaba Cloud, behind Cloudflare DNS. Built with React, Express, MariaDB, and Redis for an online lottery.

Three cloud providers managed as one production environment.
Content is delivered through CDN networks on several clouds.
Fast data access through Redis caching.

What I did

Built the frontend in React and the REST API in Express, served through Nginx.
Designed the data layer on MariaDB, with Redis for caching and in-memory data.
Managed DNS through Cloudflare.
Ran the platform across AWS, Tencent Cloud, and Alibaba Cloud, using cloud servers (EC2), object storage (S3), and CDN.

Stack

React.js
Express.js
MariaDB
Redis
Nginx
Cloudflare
Amazon EC2
Amazon S3
Tencent Cloud
Alibaba Cloud

Live demo· soonGitHub· soonArchitecture design· soon

Attendance, Payroll & Employee Management

A web application that brings attendance, payroll, leave, and employee records into one system, with a self-service portal for employees and reports for administrators.

Attendance, leave, holidays, and payroll managed in one place.
Employees get their own portal for their information.
Reports export to PDF and Excel.
The interface is available in English, Spanish, and Chinese.

What I did

Built the frontend in React and TypeScript with Vite and HeroUI.
Built the REST API in Node.js and Express on MongoDB.
Implemented JWT sign-in, password hashing, and secure HTTP headers.
Added PDF and Excel generation, email sending, and file storage on Amazon S3.
Packaged the frontend and backend as Docker images in Amazon ECR and deployed them on Amazon ECS.

Stack

React.js
TypeScript
Vite
HeroUI
Node.js
Express.js
MongoDB
JWT
Amazon S3
Docker
Amazon ECR
Amazon ECS

Live demo· soonGitHub· soonArchitecture design· soon

AWS Infrastructure as Code with Terraform

My own learning lab, where I build AWS infrastructure entirely with Terraform: CI/CD pipelines, EC2 servers, and S3 storage, all defined as code rather than set up by hand.

Every resource is created from Terraform code, with nothing configured by hand in the console.
Terraform state is stored safely, versioned, and locked against conflicting changes.
A monthly budget keeps AWS costs visible while I experiment.

What I did

Wrote a bootstrap module that creates the remote state bucket on Amazon S3.
Enabled versioning, KMS encryption, public access blocking, a bucket policy, and lifecycle rules on that bucket.
Configured an S3 backend with state locking for the dev environment.
Defined an AWS cost budget in Terraform.
Now building CI/CD pipelines, EC2 servers, and S3 storage, all from Terraform.

Stack

Terraform
Amazon Web Services (AWS)
Amazon EC2
Amazon S3
CI/CD

GitHub· soonArchitecture design· soon

Honorable mentions

ReferMe Marketplace
2025
A professional services marketplace that connects clients with trusted professionals for business and personal needs.
- Marketplace
- Web app
Visit site
ChatGroups
2024
AI chat rooms where people create songs and images live, share them instantly, and build communities around shared interests.
- Generative AI
- Communities
Visit site
AI Companion Chatbot
2024
An AI chatbot on Telegram that offers companionship through ongoing, personal conversations.
- Telegram
- LLM
School Management System
2025
A school management system for schools in Africa, including report cards, financial features, and a redesigned interface.
- Education
- Africa
ReferMe Marketplace
2025
A professional services marketplace that connects clients with trusted professionals for business and personal needs.
- Marketplace
- Web app
Visit site
ChatGroups
2024
AI chat rooms where people create songs and images live, share them instantly, and build communities around shared interests.
- Generative AI
- Communities
Visit site
AI Companion Chatbot
2024
An AI chatbot on Telegram that offers companionship through ongoing, personal conversations.
- Telegram
- LLM
School Management System
2025
A school management system for schools in Africa, including report cards, financial features, and a redesigned interface.
- Education
- Africa

Three projects that show how I work.

Online Lottery Platform

What I did

Stack

Attendance, Payroll & Employee Management

What I did

Stack

AWS Infrastructure as Code with Terraform

What I did

Stack

Honorable mentions

ReferMe Marketplace

ChatGroups

AI Companion Chatbot

School Management System

Three projects that show how I work.

Online Lottery Platform

What I did

Stack

Attendance, Payroll & Employee Management

What I did

Stack

AWS Infrastructure as Code with Terraform

What I did

Stack

Honorable mentions

ReferMe Marketplace

ChatGroups

AI Companion Chatbot

School Management System