💼 Billing & Inventory Management System

A full-stack Django-based Billing & Inventory Management System designed to simplify business operations by automating billing, stock management, and invoice generation.
It provides a seamless workflow for managing products, customers, payments, and real-time sales analytics — all in one scalable platform.

🏗️ Features

• 🔐 User Authentication — Secure access for admin and staff
• 👥 Customer Management — Add, update, and track customer details
• 📦 Product Inventory — Manage stock levels, auto-update after billing
• 🧾 Invoice System — Create, view, and print invoices in PDF format
• 💰 Payments Module — Record and track cash, UPI, card, or bank payments
• 📊 Analytics Dashboard — Visualize sales, revenue, and stock trends
• 🕓 Timezone Safe — Automatically adjusts timestamps to local timezone
• ⚙️ Responsive UI — Built with HTML5, CSS3, Bootstrap 5, and JS

🧠 Tech Stack

Layer	Technology
Backend	Django (Python)
Frontend	HTML5, CSS3, Bootstrap 5, JavaScript
Database	MySQL
PDF Generation	WeasyPrint / xhtml2pdf
Analytics	Plotly Dash
DevOps	Git, GitHub, GitHub Actions
Tools	VS Code, Postman

📂 Folder Structure

billing_system/
│
├── core/                     # Main app: customers, products, invoices, payments
│   ├── models.py             # Database models
│   ├── views.py              # Business logic and rendering
│   ├── urls.py               # Routing for core modules
│   ├── templates/            # HTML pages
│   └── static/               # CSS, JS, and images
│
├── billing_system/           # Project configuration
│   ├── settings.py
│   ├── urls.py
│   └── wsgi.py
│
└── manage.py

⚙️ Installation

1️⃣ Clone Repository

git clone https://github.com/sk-sanju/billing-system.git
cd billing-system

2️⃣ Create Virtual Environment

python -m venv venv
venv\Scripts\activate   # On Windows
source venv/bin/activate # On Mac/Linux

3️⃣ Install Dependencies

pip install -r requirements.txt

4️⃣ Database Setup

python manage.py makemigrations
python manage.py migrate

5️⃣ Create Superuser

python manage.py createsuperuser

6️⃣ Run Server

python manage.py runserver

Then visit 👉 http://127.0.0.1:8000/

🧾 Invoice Logic

• Invoice quantity cannot exceed available stock
• Stock automatically decreases upon successful billing
• If invoice item is deleted → stock is restored
• PDF invoices are auto-generated using WeasyPrint

📊 Analytics Dashboard

• Sales trends by date & category
• Revenue visualization
• Top-selling products
• Stock movement insights

🤝 Contributing

Contributions are always welcome!

1. Fork the repository
2. Create your feature branch
3. Commit changes
4. Push and create a pull request

👨‍💻 Author

Sanjay S (Sanju)
💼 Data Analyst | Python & Django Developer
🔗 GitHub | LinkedIn

🧩 License

This project is licensed under the MIT License — you’re free to modify and use it for your business or research.

⭐ Star this repo if you find it helpful!