📒 Backend Ledger

A robust Node.js/Express ledger service featuring immutable transaction logs, idempotent financial transfers, and reliable account management powered by MongoDB with secure JWT authentication.

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📑 Table of Contents

• Overview
• Architecture
• Entity Relationship Diagram
• API Reference
• Installation
• Environment Variables
• Running the App

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🔍 Overview

Backend Ledger is a production-grade financial ledger REST API built for reliability and correctness. It provides:

• 🔒 Secure Authentication — JWT-based auth for all protected routes
• 💳 Account Management — Create and manage user accounts with real-time balance tracking
• 💸 Idempotent Transfers — Safe, duplicate-proof financial transfers between accounts
• 📜 Immutable Transaction Logs — Every debit and credit is permanently recorded and auditable
• ⚡ Transactional Safety — Critical operations use MongoDB sessions to ensure data consistency
• 📄 OpenAPI Docs — Interactive Swagger UI for exploring and testing all endpoints

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🏗 Architecture

📐 For a detailed in-depth explanation of the system design, module responsibilities, and data flow, refer to the docs/ARCHITECTURE.md file.

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🗃 Entity Relationship Diagram

📊 For the full interactive ERD with detailed column types, constraints, and relationships, visit dbdocs.io — Backend Ledger Project.

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📡 API Reference

The API is organized around the following core resource groups:

Group	Base Path	Description
Auth	/api/auth	Register, login, and token management
Accounts	/api/accounts	Create and manage ledger accounts
Transfers	/api/transfers	Initiate idempotent fund transfers
Ledger	/api/ledger	View immutable transaction history

All endpoints follow RESTful conventions and return JSON responses. Protected routes require a Bearer token in the Authorization header.

📖 For the complete interactive API documentation including request/response schemas, authentication flows, and a live try-it-out console, visit: https://backend-ledger-tbxj.onrender.com/api/docs/

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⚙️ Installation

Prerequisites

Make sure you have the following installed:

• Node.js v18 or higher
• npm v9 or higher
• MongoDB v6 or higher (local) or a MongoDB Atlas cluster

Steps

1. Clone the repository

git clone https://github.com/omprakash0224/Backend-Ledger.git
cd Backend-Ledger

2. Install dependencies

npm install

3. Set up environment variables

cp .env.example .env

Then edit .env with your configuration (see Environment Variables below).

4. Configure your MongoDB connection

Set your MongoDB connection string in .env (see Environment Variables below). You can use a local MongoDB instance or a free MongoDB Atlas cluster — no manual schema setup is needed as Mongoose handles collection creation automatically.

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🔐 Environment Variables

Create a .env file in the root directory with the following variables:

MONGO_URI=your_mongodb_uri_here
JWT_SECRET=your_jwt_secret_here
CLIENT_ID=your_google_client_id_here
CLIENT_SECRET=your_google_client_secret_here
REFRESH_TOKEN=your_google_refresh_token_here
EMAIL_USER=your_email_user_here

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🚀 Running the App

Development mode (with auto-reload):

npm run dev

Production mode:

npm start

The server will start at http://localhost:3000 by default.

The interactive API docs will be available at http://localhost:3000/api/docs/.

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Made with ❤️ by omprakash0224