Next.js
Node.js (Express)
Sequelize ORM
MySQL
Redis
Azure Blob Storage
Docker
VercelThe Problem & Challenge
To demonstrate the DigiPay Payment Gateway integration process to clients, the company proposed developing a Multi-Vendor Marketplace prototype. This system simulates a real-world multi-vendor environment, featuring comprehensive administrative controls and reliable transaction reversal workflows (Voids and Refunds) modeled precisely after live payment gateway API behaviors.
The Engineering Solution
I architected the database schema and system workflows from scratch. I developed the merchant portal and backoffice administrator dashboards using Next.js 15, Express.js, and Sequelize ORM on a MySQL database. I implemented real-time transaction void and refund pipelines integrated with DigiPay APIs, stored product assets securely on Azure Blob Storage, implemented asymmetric JWT security utilizing RSA Key Pairs, and automated administrator onboarding flows via the SendGrid API.
Technical System Architecture
Client-Server architecture separating frontend portals (Next.js 15) from backend REST APIs (Express.js) and MySQL database.
DigiPay API integration managing transaction status queries, voids (un-settled approved), and refunds (settled captured) flows.
Secured JWT authentication using asymmetric RSA Key Pairs and Role-Based Access Control (RBAC) middleware.
Store profile and product image uploads stored on Azure Blob Storage, securely accessed via Shared Access Signature (SAS) URLs.
Onboarding workflow sending administrative invitations and password setup links via secure tokens using the SendGrid API.
Containerized development environment using Docker, deployed on Railway (Backend & DB) and Vercel (Frontend).
Key System Highlights
DigiPay Refund Flow
Executes transaction reversals with Voids for APPROVED transactions and Refunds for SETTLED transactions using the DigiPay API.
Asymmetric JWT Security
Protects administrative and merchant API endpoints using RSA Key Pairs for JSON Web Tokens (JWT) and RBAC middleware.
SendGrid Invite Streams
Dispatches administrative invitations and password setup flows using secure, encrypted tokens via the SendGrid API.
Dockerized DevOps
Containerizes system components using Docker to simplify setup and deployment across Railway and Vercel.