PyBill

Billing Software - python based lightweight, native desktop application

Project Overview

A robust desktop billing software solution designed for small to medium-sized businesses, providing end-to-end management of sales, inventory, and customer interactions.

Technical Architecture

Core Technologies

• Language: Python 3.8+

• Frontend: Tkinter (Native Desktop GUI)

• Database: SQLite with potential future scalability to PostgreSQL

• Security: Bcrypt password hashing

• Recommended Approach:

  • Use modern Tkinter widgets (Treeview, Notebook)
  • Implement responsive design principles
  • Create modular UI components for easy maintenance

System Architecture

1. Authentication & Security System

User Roles

• Admin Role:

  • Full system access
  • Manage user accounts
  • Configure product catalog
  • Access comprehensive system settings

• Staff Role:

  • Limited permissions
  • Create invoices
  • Process payments
  • View restricted information

Security Features

• Bcrypt one-way password encryption
• Unique salt generation for each password
• Login attempt tracking
• Role-based access control (RBAC)

2. Product Management Module

Functionality

• Create, Read, Update, Delete (CRUD) operations
• Real-time inventory tracking
• Product categorization
• Stock level monitoring

Validation Mechanisms

• Prevent negative stock entries
• Enforce unique product names
• Validate pricing information
• Automatic low-stock alerts

3. Customer Management Module

Key Features

• Comprehensive customer profile creation
• Advanced search capabilities
• Contact information management
• Customer history tracking

Search Capabilities

• Quick lookup by:
  • Name
  • Email
  • Phone number
• Fuzzy search implementation

4. Invoice Generation System

Core Capabilities

• Dynamic product selection
• Real-time quantity adjustment
• Automatic total calculation
• Flexible discount application
• PDF export functionality

Export Features

• Professional invoice templates
• Detailed transaction breakdowns
• Customizable formatting

5. Payment Processing Module

Supported Payment Methods

• Cash transactions
• Credit/Debit card payments
• Potential future integration with online payment gateways

Payment Tracking

• Link payments to specific invoices
• Track payment status
• Generate alerts for pending transactions
• Comprehensive payment history

Project Structure

billing_software/
│
├── config/           # Database and application configuration
│   └── database.py   # Connection settings
│
├── models/           # Data models and business logic
│   ├── user.py       # Authentication and user management
│   ├── product.py    # Product-related operations
│   ├── customer.py   # Customer data handling
│   └── invoice.py    # Invoice generation logic
│
├── views/            # User interface components
│   ├── login_view.py # Authentication screen
│   ├── dashboard.py  # Main application interface
│   └── invoice_view.py # Invoice creation UI
│
├── controllers/      # Business logic and data processing
│   ├── auth_controller.py
│   ├── product_controller.py
│   └── invoice_controller.py
│
├── utils/            # Utility functions
│   ├── validators.py # Input validation
│   └── security.py   # Encryption and security utilities
│
├── tests/            # Comprehensive test suite
│   ├── test_authentication.py
│   ├── test_product_management.py
│   └── test_invoice_generation.py
│
├── resources/        # Static assets
│   ├── icons/
│   └── templates/
│
├── main.py           # Application entry point
└── requirements.txt  # Project dependencies

Database Schema

Primary Tables

1. Users

   • Unique ID
   • Username
   • Hashed Password
   • Role
   • Creation Timestamp

2. Categories

   • ID
   • Name
   • Description
   • Creation Timestamp

3. Products

   • Unique ID
   • Name
   • Category
   • Price
   • Current Stock
   • Creation Timestamp

4. Customers

   • Unique ID
   • Full Name
   • Contact Information
   • Address
   • Registration Timestamp

5. Invoices

   • Invoice Number
   • Customer ID
   • Total Amount
   • Discount Applied
   • Creation Timestamp

6. Invoice Items

   • Line Item ID
   • Invoice ID
   • Product ID
   • Quantity
   • Subtotal

7. Payments

   • Payment ID
   • Invoice ID
   • Amount Paid
   • Payment Method
   • Timestamp

Development Roadmap

Phase 1: Foundation

• Database schema design
• Authentication system
• Basic UI structure

Phase 2: Core Modules

• Product management
• Customer management
• Invoice generation

Phase 3: Advanced Features

• Payment processing
• Reporting capabilities
• PDF export functionality

Phase 4: Optimization

• Performance tuning
• Security hardening
• User experience refinement

Potential Future Enhancements

• Cloud backup integration
• Multi-user support
• Advanced reporting and analytics
• Mobile companion app

Recommended Libraries

• Tkinter: GUI development
• SQLite3: Database management
• Bcrypt: Password security
• ReportLab/FPDF: Invoice generation
• Datetime: Timestamp operations

Conclusion

A scalable, secure, and user-friendly billing solution designed to streamline business operations with a focus on reliability and future extensibility.