GST Invoice & Inventory Management System

An enterprise-grade, high-performance GST Invoice & Inventory ERP Application tailored for Indian Small and Medium Businesses (SMBs). Built on Laravel 13, Livewire 3, Tailwind CSS, and DomPDF, with automated intra-state (CGST + SGST) and inter-state (IGST) tax calculation, sequential invoice numbering, stock audit trails, asynchronous PDF generation, and multi-tenant isolation.

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🌟 Key Features

• ⚡ Real-Time GST Engine (Livewire 3):

  • Automated state detection based on 15-digit GSTIN (e.g., 27 for Maharashtra, 24 for Gujarat).
  • Dynamic intra-state (50% CGST + 50% SGST) and inter-state (100% IGST) tax calculations without full-page reloads.
  • Indian currency words converter (Lakhs & Crores) for legal tax compliance.

• 📦 Inventory & Double-Entry Stock Ledger:

  • Immutable audit trail in stock_moves table for every sale, purchase, and stock adjustment.
  • Pessimistic locking (lockForUpdate) to prevent negative inventory during simultaneous billings.
  • Low stock warning badges and reorder notifications.

• 📄 Official GST Tax Invoice PDF (barryvdh/laravel-dompdf):

  • Compliant GST Rule 46 printable tax invoices with HSN/SAC breakdowns, seller/buyer state codes, terms, and signature blocks.
  • Asynchronous background rendering and customer email notifications via queued jobs (SendInvoiceEmailJob).

• 📊 High-Performance Executive Dashboard:

  • Multi-level caching with automatic Model Observer invalidation (InvoiceObserver, StockMoveObserver).
  • Real-time summaries of monthly turnover, total GST collected, active invoices, and low stock warnings.

• 🛡️ Enterprise Security & RBAC:

  • Role-Based Access Control (admin, sales, accountant) with Laravel Policies (InvoicePolicy, ProductPolicy, CustomerPolicy).
  • Strict multi-tenant data boundaries preventing cross-tenant data access (IDOR protection).
  • Custom validation rules for Indian GSTIN (GstinRule) and HSN/SAC codes (HsnCodeRule).

• 🔌 REST API & Performance:

  • Clean API Resource transformers (ProductResource, InvoiceResource) with cursor pagination and rate limiting (throttle:60,1).

• 🧪 100% Automated Test Coverage (Pest PHP):

  • Unit tests for tax algorithms and currency formatters.
  • Feature tests for invoice creation, stock deduction, and tenant isolation policies.

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🏗️ Architecture & Technology Stack

Component	Technology
Backend Framework	Laravel 13 (PHP 8.3+)
Reactivity Layer	Livewire 3 + Volt + Alpine.js
Styling & UI	Tailwind CSS (Emerald/Slate Theme)
PDF Generation	barryvdh/laravel-dompdf (v3.1+)
Testing Engine	Pest PHP (v5.x)
Authentication	Laravel Breeze (Livewire Stack)
Database	MySQL / MariaDB / SQLite with indexed composite lookups

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🚀 Local Installation & Setup

Prerequisites

• PHP >= 8.3 with bcmath, ctype, fileinfo, json, mbstring, pdo, tokenizer, xml extensions.
• Composer 2.x
• Node.js (v18+) & NPM

Setup Instructions

# 1. Clone the repository
git clone https://github.com/kmtech183/gst-invoice.git
cd gst-invoice

# 2. Install Composer dependencies
composer install

# 3. Setup environment configuration
cp .env.example .env
php artisan key:generate

# 4. Configure Database in .env and run migrations with seed data
php artisan migrate:fresh --seed

# 5. Install frontend packages and build assets
npm install
npm run build

# 6. Start development server
php artisan serve

Default Demo Credentials (from Seeder)

Role	Email	Password
Admin	[email protected]	password
Sales	[email protected]	password
Accountant	[email protected]	password

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🧪 Running Automated Tests

php artisan test

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📄 License

This project is open-sourced software licensed under the MIT License.