InsightPay: Smart Digital Wallet & Personal Finance Platform

InsightPay is a secure, full-stack digital wallet and personal finance platform that supports user authentication, multi-method wallet ledger transactions, QR-based payments, tokenized card management, subscription tracking, and automated bill splitting.

---

Interface Preview

UI Screenshots

Landing Page

Personal Finance Dashboard

Saved Cards Management

---

Core Features & Engineering Highlights

• Secure Authentication & Session Management: Stateless JWT-based session architecture with bcrypt-hashed credentials and HTTP-only cookie-like practices.
• Double-Entry Ledger Architecture: Financial transfers, balance updates, and settlements are executed within isolated SQL transactions to maintain ledger integrity.
• QR-Based Payment Pipeline: Secure cryptographic signing and verification of dynamic merchant/user QR codes.
• Tokenized Card Management: Dynamic frontend credit card layout rendering with automatic issuer brand recognition (Visa, Mastercard, RuPay, Amex) and tailored visual theme mappings (HDFC, SBI, ICICI, AXIS).
• Dynamic Visual Conflict Resolution: Employs a custom layout constraint resolver that programmatically formats and truncates cardholder names dynamically to fit text boundaries (under 14 characters) and prevent overlap with valid-thru dates.
• Interactive Spending Analytics: Visual spend distributions by category using fully interactive custom CSS-rendered charts and tooltips.
• Split-Bill Requests: Integrated ledger request triggers to split balances and record settling transactions among users.

---

Technical Architecture & Design Decisions

ACID-Compliant Financial Transfers

To eliminate double-spend vulnerabilities and ensure race-condition resilience during balance transfers and split settlements, the platform utilizes database-level row locks and isolated Prisma.$transaction calls. If any step of the debit-credit pipeline fails (e.g. sender has insufficient funds, receiver account is deactivated, database writes timeout), the entire ledger write is rolled back safely:

// Sample transaction enforcement block in the wallet ledger repository
await prisma.$transaction(async (tx) => {
  // 1. Lock sender wallet and check balance
  const senderWallet = await tx.wallet.update({
    where: { userId: senderId },
    data: { balance: { decrement: amount } }
  });
  
  if (senderWallet.balance < 0) {
    throw new Error("Insufficient funds");
  }

  // 2. Increment receiver wallet
  await tx.wallet.update({
    where: { userId: receiverId },
    data: { balance: { increment: amount } }
  });

  // 3. Record transaction entry
  await tx.transaction.create({
    data: { senderId, receiverId, amount, type: 'TRANSFER', status: 'SUCCESS' }
  });
});

Decoupled Codebase Structure

The codebase follows a clean separation of concerns, grouping components by feature boundary:

insightpay/
├── backend/                  # Node.js + Express API service
│   ├── prisma/               # Schema configuration and migrations
│   └── src/                  # Express endpoints grouped by resource boundaries
│       ├── features/         # auth, cards, categories, qr, transactions, wallet, splits
│       ├── middlewares/      # auth check, rate limiting, error handlers
│       └── server.js
│
└── frontend/                 # React SPA
    └── src/
        ├── app/              # Router and global provider definitions
        ├── features/         # Page components and state hooks isolated by domain
        └── shared/           # Generic buttons, input templates, logos, API hooks

---

Tech Stack

Category	Technology	Purpose
Frontend	React, TypeScript, Vite	Scalable, typed SPA execution
Styling	Tailwind CSS	Utility-first component layouts
Database	MySQL, Prisma ORM	SQL storage engine & transactional migration engine
Backend	Node.js, Express	RESTful API service orchestrator
Security	bcrypt, Helmet, Express Rate Limit	API request defense & hashing integrity

---

Database Schema Outline

• User: Hashed credentials, profile mapping, and relationship links.
• Transaction: Ledger tracking containing amount, type (TRANSFER, ADD_MONEY, QR_PAY), category, and status.
• Card: Saved payment cards referencing user accounts.
• Category: Financial grouping structures supporting default system configurations and customized user categories.
• Subscription: Recursive billing tracker tied to card tokens.
• SplitRequest: Collaborative ledger records for peer-to-peer bill splitting.

---

Getting Started

Prerequisites

• Node.js (v18+)
• MySQL Server Instance
• npm

Backend Setup

1. Navigate to directory and install dependencies:

   cd backend
   npm install

2. Configure .env environment file:

   DATABASE_URL="mysql://USER:PASSWORD@localhost:3306/insightpay"
   JWT_SECRET="your_secure_jwt_secret"
   QR_SECRET="your_secure_qr_secret"
   PORT=8000

3. Run database migrations and generate Prisma clients:

   npx prisma migrate dev
   npx prisma generate

4. Run the Express dev server:

   npm run dev

Frontend Setup

1. Navigate to directory and install dependencies:

   cd ../frontend
   npm install

2. Start the Vite dev server:

   npm run dev

3. Launch http://localhost:5173 in your browser.