🧾 Invoice Generator

A flexible and developer-friendly tool to generate professional invoices from structured input data. Supports line items, tax, discounts, and optional HTML output.

---

🚀 Features

• 🧩 Structured invoice generation from JSON input
• 📦 Supports multiple line items with quantity and pricing
• 💰 Automatic subtotal, tax, discount, and total calculation
• 🌐 Optional HTML invoice generation
• 🛡️ Strong input validation with strict schema
• 🔌 Easy integration into APIs, automation tools, and workflows

---

📥 Input Schema

Field	Type	Required	Description
invoiceNumber	string	❌ No	Unique invoice ID (default: INV-001)
issueDate	string	❌ No	Format: YYYY-MM-DD (defaults to today)
dueDate	string	❌ No	Format: YYYY-MM-DD (defaults to +30 days)
fromName	string	✅ Yes	Sender name or company
fromAddress	string	❌ No	Sender address
fromEmail	string	❌ No	Sender email
toName	string	✅ Yes	Recipient name or company
toAddress	string	❌ No	Recipient address
toEmail	string	❌ No	Recipient email
items	array	✅ Yes	List of invoice items
taxRate	number	❌ No	Tax percentage (0–100)
discountPercent	number	❌ No	Discount percentage (0–100)
currency	string	❌ No	Currency symbol (default: $)
notes	string	❌ No	Notes or payment terms
generateHTML	boolean	❌ No	Generate HTML invoice (default: true)

---

📦 Line Item Format

Each item in the items array must follow:

{
  "description": "Web development service",
  "quantity": 2,
  "unitPrice": 150
}

---

⚙️ How It Works

💵 Calculations

1. Subtotal

subtotal = sum(quantity × unitPrice)

2. Discount

discount = subtotal × (discountPercent / 100)

3. Tax

tax = (subtotal - discount) × (taxRate / 100)

4. Total

total = subtotal - discount + tax

---

🧮 Example

Input

{
  "fromName": "Umar Tech",
  "toName": "Client Inc.",
  "items": [
    { "description": "API Development", "quantity": 1, "unitPrice": 500 },
    { "description": "Hosting", "quantity": 2, "unitPrice": 50 }
  ],
  "taxRate": 10,
  "discountPercent": 5
}

Output

{
  "subtotal": 600,
  "discount": 30,
  "tax": 57,
  "total": 627
}

---

🏗️ Use Cases

• Freelancers generating invoices
• SaaS billing systems
• Automation pipelines (Apify, scripts, etc.)
• Backend invoice services
• Client billing dashboards

---

🌐 HTML Output

If generateHTML is enabled, the tool returns a ready-to-use invoice template that can be:

• Rendered in a browser
• Converted to PDF
• Sent via email

---

⚡ Notes

• If dates are not provided, defaults are automatically applied
• At least one item is required in the invoice
• Discounts are applied before tax calculation
• Currency symbol is customizable

---

🛠️ Example Logic (Pseudo Code)

subtotal = sum(item["quantity"] * item["unitPrice"] for item in items)
discount = subtotal * (discountPercent / 100)
tax = (subtotal - discount) * (taxRate / 100)
total = subtotal - discount + tax

---

📄 License

MIT License