D-App Backend (MERN) — Semi DApp with Wallet & Card Payments

Overview

A backend for a semi-decentralized application (Semi DApp) built with the MERN stack.
Supports on-chain interactions (read-only or signed transactions via connected wallet), an off-chain wallet system, and card payments (PCI-compliant via a payment gateway). Designed for modularity, security, and easy deployment.

Key Features

• RESTful API built with Express and Node.js
• MongoDB database for application and user data
• JWT authentication + refresh tokens
• On-chain integration (Ethereum-compatible networks) via ethers.js / web3.js
• Card payments integration (Stripe behind a payment service)
• Idempotent deposit/withdraw flows and reconciliations
• Role-based access control (admin, user, auditor)
• Auditable transaction log and webhook handlers
• Rate limiting, input validation, and logging

Architecture (high level)

1. API Layer — Express routes, validation, controllers
2. Service Layer — Business logic (payments, wallets, on-chain ops)
3. Data Layer — Mongoose models and repositories
4. External Integrations — Payment gateway, blockchain node/provider, email/SMS provider

Recommended Tech Stack

• Node.js (LTS)
• Express
• MongoDB (Atlas or self-hosted)
• Mongoose
• ethers.js (or web3.js)
• Stripe (card payments) or another PCI-compliant gateway
• Jest / Supertest for tests