🏦 FastAPI Banking System

A production-style Bank Account Management API built with FastAPI, SQLAlchemy, and MySQL.

Designed to simulate real-world fintech backend systems with secure authentication, transactional integrity, and rule-based financial operations.

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🖼️ UI Preview

Watch Full Demo:- https://youtu.be/iex0donzgtE

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🌐 Live Demo

• Frontend: https://fastapi-banking-system.vercel.app
• Backend API: https://fastapi-banking-system.onrender.com
• API Docs: https://fastapi-banking-system.onrender.com/docs

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🚀 Key Features

🔐 Authentication

• JWT-based authentication
• Secure password hashing (bcrypt)
• Case-insensitive username handling
• Protected routes using dependency injection

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🏦 Account Management

• Create multiple accounts per user
• Unique account number enforcement
• Accounts initialized with zero balance (system-controlled)
• Fetch all user accounts securely

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🔄 Account Lifecycle (NEW)

Accounts are not physically deleted. Instead, they are marked as:

• ACTIVE → usable account
• CLOSED → hidden from UI and blocked from operations

This ensures:

• Data integrity
• Transaction history preservation
• Real-world banking behavior

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💸 Transactions (Core System)

✔ Supported Operations

• Deposit funds
• Withdraw funds with balance validation
• Transfer money between accounts

✔ Safety & Integrity

Prevent overdraft (no negative balance)

• Prevent overdraft (no negative balance)
• Prevent self-transfers
• Only ACTIVE accounts can perform operations
• Atomic database transactions using commit/rollback

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🧠 Business Rules & Financial Constraints

💰 Transaction Limits

• Deposit limit per transaction
• Withdraw limit per transaction
• Transfer limit enforcement

Limits are centrally managed via a config module, making the system flexible and maintainable.

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🧾 Transaction Ledger

• Every operation (deposit, withdraw, transfer) is recorded

• Enables audit tracking and system transparency

• Foundation for future features like:

  • Statements
  • Analytics
  • Fraud detection

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🧠 Validation Strategy

• Strong input validation using Pydantic schemas

• Backend-driven validation (never trusting frontend)

• Ownership-based authorization

• SClean separation of validation and business logic:

  • Data validation (schemas)
  • Business logic (routes/services)

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🧱 Tech Stack

Layer	Technology
Backend	FastAPI
ORM	SQLAlchemy
Database	MySQL
Validation	Pydantic
Auth	JWT (python-jose)
Security	Passlib (bcrypt)
Config	python-dotenv

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📁 Project Structure

fastapi-banking-system/
│
├── app/
│   ├── routes/        # API endpoints    
│       (auth, accounts, transactions)
│   ├── models/        # Database models
│   ├── schemas/       # Request/response validation
│   ├── db/            # DB connection setup
│   ├── core/          # Security, config (JWT, hashing, limits)
│   └── dependencies/  # Auth middleware
│
├── main.py
├── requirements.txt
├── .env
└── .gitignore

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⚙️ Setup Guide

1️⃣ Clone Repository

git clone https://github.com/Dhruv-Cmds/fastapi-banking-system.git
cd fastapi-banking-system

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2️⃣ Create Virtual Environment

python -m venv .venv

Activate:

Windows

.venv\Scripts\activate

Mac/Linux

source .venv/bin/activate

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3️⃣ Install Dependencies

pip install -r requirements.txt

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4️⃣ Configure Environment

Create a .env file:

DB_USER=root
DB_PASSWORD=your_password
DB_HOST=localhost
DB_NAME=bankaccountsystem

SECRET_KEY=your_secret_key
ALGORITHM=HS256
ACCESS_TOKEN_EXPIRE_MINUTES = your_time

IF You Want to go live: 

MYSQL_PUBLIC_URL = your_url

SECRET_KEY=your_secret_key
ALGORITHM=HS256
ACCESS_TOKEN_EXPIRE_MINUTES = your_time

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5️⃣ Run Server

uvicorn main:app --reload (backend)
npm run dev (frontend)

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📌 API Endpoints

🔐 Auth

• POST /signup
• POST /login

🏦 Accounts

• POST /accounts
• GET /accounts
• DELETE /accounts/{id} → closes account

💰 Transactions

• POST /accounts/{id}/deposit
• POST /accounts/{id}/withdraw
• POST /transfer

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🧠 System Behavior

• Tables auto-created at startup:

Base.metadata.create_all(bind=engine)

• Account lifecycle:

Create account → balance = 0  
Deposit → increases balance  
Withdraw → decreases balance  
Transfer → moves funds safely 
Close account → status = CLOSED (not deleted) 

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🔐 Security Highlights

• JWT authentication
• Password hashing (bcrypt)
• Environment-based secrets
• Ownership-based authorization checks
• Safe transaction handling using DB locks
• Protection against race conditions

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💎 Highlights

• Clean, modular architecture
• Real-world banking logic implementation
• Soft-delete system (account lifecycle)
• Transaction safety (race-condition prevention)
• Rule-based financial system (limits + validation)
• Scalable backend design

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🏁 Conclusion

This project demonstrates how to build a real-world backend system with:

• Authentication & authorization
• Database design & ORM usage
• Transaction safety & concurrency handling
• Business rule enforcement
• Clean architecture & scalability

It serves as a strong foundation for evolving into a full fintech platform 🚀

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⭐ Author

Dhruv Backend-focused developer building systems with strong fundamentals in API design, data integrity, and system thinking.