API Documentation

Everything you need to generate invoice PDFs

Authentication

All API requests require an API key. Include it in the X-API-Key header:

X-API-Key: your_api_key

Don't have an API key? Get one for free.

Base URL

https://pdfbill.io/api/v1

Endpoints

POST /invoice

Generate an invoice PDF from JSON data.

Request Headers

Header	Value
`X-API-Key`	Your API key required
`Content-Type`	`application/json`

Request Body

Field	Type	Description
`template`	string	optional Template style: `modern`, `classic`, or `minimal`. Default: `modern`
`invoice_number`	string	optional Invoice number. Default: `INV-001`
`date`	string	optional Issue date (YYYY-MM-DD). Default: today
`due_date`	string	optional Due date (YYYY-MM-DD)
`from`	object	optional Sender information
`from.name`	string	Company/person name
`from.address`	string	Address
`from.email`	string	Email address
`to`	object	optional Recipient information
`to.name`	string	Company/person name
`to.address`	string	Address
`to.email`	string	Email address
`items`	array	required Line items
`items[].description`	string	Item description
`items[].quantity`	number	Quantity
`items[].price`	number	Unit price
`tax_rate`	number	optional Tax rate as percentage (e.g., 10 for 10%)
`currency`	string	optional Currency symbol. Default: `$`
`notes`	string	optional Additional notes

Example Request

curl -X POST https://pdfbill.io/api/v1/invoice \
  -H "X-API-Key: your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "template": "modern",
    "invoice_number": "INV-2025-001",
    "date": "2025-12-01",
    "due_date": "2025-12-15",
    "from": {
      "name": "Your Company",
      "address": "123 Main St, City, Country",
      "email": "billing@yourcompany.com"
    },
    "to": {
      "name": "Client Company",
      "address": "456 Client Ave, City, Country",
      "email": "accounts@client.com"
    },
    "items": [
      {"description": "Web Development", "quantity": 10, "price": 150},
      {"description": "Hosting (Monthly)", "quantity": 1, "price": 29}
    ],
    "tax_rate": 10,
    "currency": "$",
    "notes": "Payment due within 14 days."
  }' \
  -o invoice.pdf

Response

Returns the PDF file as binary data with:

Header	Value
`Content-Type`	`application/pdf`
`Content-Disposition`	`attachment; filename="invoice.pdf"`

Error Responses

Status Code	Description
`400`	Bad request - Invalid input data or unknown template
`401`	Unauthorized - Missing or invalid API key
`500`	Server error - Something went wrong

Error Response Format

{
  "error": "Error message here"
}

Templates

Choose a template style by setting the template field:

Template	Description
`modern`	Clean, professional design with blue accents. Great for tech companies.
`classic`	Traditional, formal design with serif fonts. Perfect for enterprises.
`minimal`	Simple, elegant design with lots of whitespace. Ideal for startups.

Rate Limits

Plan	Invoices per Month
Free	50
Starter ($9/mo)	500
Pro ($29/mo)	2,000

Code Examples

Node.js

const fs = require('fs');

const response = await fetch('https://pdfbill.io/api/v1/invoice', {
  method: 'POST',
  headers: {
    'X-API-Key': 'your_api_key',
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    template: 'modern',
    invoice_number: 'INV-001',
    from: { name: 'Your Company' },
    to: { name: 'Client' },
    items: [{ description: 'Service', quantity: 1, price: 100 }]
  })
});

const buffer = await response.arrayBuffer();
fs.writeFileSync('invoice.pdf', Buffer.from(buffer));

Python

import requests

response = requests.post(
    'https://pdfbill.io/api/v1/invoice',
    headers={
        'X-API-Key': 'your_api_key',
        'Content-Type': 'application/json',
    },
    json={
        'template': 'modern',
        'invoice_number': 'INV-001',
        'from': {'name': 'Your Company'},
        'to': {'name': 'Client'},
        'items': [{'description': 'Service', 'quantity': 1, 'price': 100}]
    }
)

with open('invoice.pdf', 'wb') as f:
    f.write(response.content)

PHP

$ch = curl_init('https://pdfbill.io/api/v1/invoice');

curl_setopt_array($ch, [
    CURLOPT_POST => true,
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER => [
        'X-API-Key: your_api_key',
        'Content-Type: application/json',
    ],
    CURLOPT_POSTFIELDS => json_encode([
        'template' => 'modern',
        'invoice_number' => 'INV-001',
        'from' => ['name' => 'Your Company'],
        'to' => ['name' => 'Client'],
        'items' => [['description' => 'Service', 'quantity' => 1, 'price' => 100]]
    ])
]);

$pdf = curl_exec($ch);
file_put_contents('invoice.pdf', $pdf);