SENTINEL Marketplace
A revolutionary marketplace that combines traditional e-commerce with blockchain technology. Sentinel issues tamper-proof digital warranties (NFTs) for every purchase, verified on the Ethereum Sepolia testnet to prevent counterfeit claims.
The Challenge
Counterfeit luxury goods and fake warranty certificates are a massive issue in the secondary market. Paper warranties are easily forged, lost, or damaged, making it difficult for buyers to verify the authenticity and history of a product.
The Solution
We engineered a decoupled architecture where the Next.js frontend interacts with a Node.js/Express backend and Ethereum Smart Contracts. Every purchase via Midtrans triggers the minting of a 'Digital Twin' (NFT warranty) recorded immutably on the blockchain, providing a transparent history from retailer to consumer.
Key Features
Technology Stack
Next.js 16
Frontend framework with App Router and Server Actions.
Solidity
Smart Contract logic for warranty minting and verification.
Midtrans
Payment Gateway integration for secure fiat transactions.
Express.js
Backend REST API handling business logic and Web3 interactions.
Development Process
Research & Smart Contract Design
Designing the ERC-721 structure to represent warranties as unique, transferable assets.
Parallel Development
Simultaneously building the Next.js frontend UI and the Node.js backend API.
Integration Phase
Connecting the frontend to Midtrans for payments, which then triggers the backend to mint the NFT on Sepolia.
Testing & Validation
Simulating purchase flows, verifying transaction hashes on Etherscan, and ensuring gas optimization.
Final Presentation
Demonstrating the full lifecycle from purchase to blockchain verification.
Engineering Challenges
Transaction Latency
Blockchain transactions are slow. We implemented a queue system where the UI updates instantly (Optimistic UI) while the blockchain confirms in the background.
Gas Fees Management
To keep costs low for users, we optimized the Smart Contract storage and used the Sepolia Testnet for demonstration.