Invoice Automation System - PHP Invoice Generator

A lightweight, framework-free PHP invoice automation system that lets you manage clients, create invoices with line items, and send them directly to clients via SMTP email. Built-in automatic overdue payment reminders keep your cash flow on track without manual follow-ups. Supports both SQLite and MySQL, so it runs on any shared hosting with zero setup. No Composer, no Node.js, no framework — just upload and go.

Features

• Client management (add, edit, delete)
• Invoice creation with multiple line items, tax calculation, and custom notes
• Send invoices to clients via SMTP email (Gmail, Yahoo, cPanel, or any SMTP provider)
• Automatic overdue payment reminders on configurable days (e.g., 3, 7, 14 days after due date)
• Public invoice viewing page with print/save-as-PDF support
• Client payment page with bank transfer, mobile money, and custom instructions
• Dashboard with revenue stats, outstanding balances, and recent invoices
• Support for both SQLite (zero-config) and MySQL
• Customizable: company info, currency, tax rate, invoice prefix, base URL
• Clean, responsive admin interface
• No framework, no Composer, no build step — plain PH

Requirements

• PHP 7.4 or higher
• PDO extension enabled
• SQLite 3.x or MySQL 8.0 / MariaDB 10.x+
• SMTP account for sending emails (Gmail App Password, cPanel, or any SMTP provider)
• cPanel or equivalent shared hosting (or any LAMP/LEMP stack)
• No database pre-installation needed — includes auto-installer for SQLit

Instructions

Step 1: Upload all files to your web server (cPanel → File Manager or FTP). Step 2: Visit install.php in your browser (e.g., yoursite.com/invoice-automation/install.php). This creates the SQLite database and default settings automatically. Step 3: Delete install.php from your server after successful installation. Step 4: Visit login.php to register your admin account. The first user registered automatically becomes the admin. Step 5: Go to Settings and fill in your company information (name, email, phone, address, currency, tax rate, invoice prefix, base URL). Step 6: In Settings, configure your SMTP email (host, port, username, app password, from address). For Gmail, generate an App Password at myaccount.google.com/apppasswords. Step 7: Add your clients under Clients. Step 8: Create invoices under Invoices. Add line items, set dates, and optionally send the invoice to the client by email immediately. Step 9: Use the Dashboard to track revenue, outstanding balances, and send overdue reminders in bulk. Optional: To use MySQL instead of SQLite, edit config/config.php and change $db_type to 'mysql', then fill in your database credentials