How to Generate PDFs in Node.js

Generating PDFs from HTML is a common requirement for many applications. Whether you're creating invoices, reports, or certificates, having a reliable PDF generation solution is essential. In this guide, we'll show you how to use Doc API to generate PDFs in Node.js.

Why Use an API for PDF Generation?

Traditional approaches to PDF generation often involve:

Heavy dependencies: Libraries like Puppeteer require Chromium, adding 100MB+ to your deployment
Complex setup: Configuring headless browsers and managing memory
Scaling issues: Each PDF generation consumes significant server resources

Using an API like Doc API eliminates these problems by offloading the work to our servers.

Quick Start

Here's how to generate your first PDF with just a few lines of code:

const response = await fetch('https://api.docapi.co/v1/pdf', {
  method: 'POST',
  headers: {
    'x-api-key': 'your-api-key',
    'Content-Type': 'application/json'
  },
  body: JSON.stringify({
    html: '<h1>Hello World</h1>'
  })
});
 
const pdf = await response.arrayBuffer();

Complete Example

Let's build a more complete example that generates an invoice PDF:

import fs from 'fs';
 
async function generateInvoice(invoiceData) {
  const html = `
    <!DOCTYPE html>
    <html>
      <head>
        <style>
          body { font-family: Arial, sans-serif; padding: 40px; }
          .header { border-bottom: 2px solid #333; padding-bottom: 20px; }
          .invoice-number { color: #666; }
          table { width: 100%; border-collapse: collapse; margin-top: 30px; }
          th, td { padding: 12px; text-align: left; border-bottom: 1px solid #ddd; }
          .total { font-size: 1.2em; font-weight: bold; }
        </style>
      </head>
      <body>
        <div class="header">
          <h1>Invoice</h1>
          <p class="invoice-number">#${invoiceData.number}</p>
        </div>
        <table>
          <thead>
            <tr>
              <th>Item</th>
              <th>Quantity</th>
              <th>Price</th>
            </tr>
          </thead>
          <tbody>
            ${invoiceData.items.map(item => `
              <tr>
                <td>${item.name}</td>
                <td>${item.quantity}</td>
                <td>$${item.price}</td>
              </tr>
            `).join('')}
          </tbody>
        </table>
        <p class="total">Total: $${invoiceData.total}</p>
      </body>
    </html>
  `;
 
  const response = await fetch('https://api.docapi.co/v1/pdf', {
    method: 'POST',
    headers: {
      'x-api-key': process.env.DOCAPI_KEY,
      'Content-Type': 'application/json'
    },
    body: JSON.stringify({ html })
  });
 
  if (!response.ok) {
    throw new Error(`PDF generation failed: ${response.statusText}`);
  }
 
  return response.arrayBuffer();
}
 
// Usage
const invoice = {
  number: 'INV-001',
  items: [
    { name: 'Web Development', quantity: 1, price: 1500 },
    { name: 'Hosting (1 year)', quantity: 1, price: 200 }
  ],
  total: 1700
};
 
const pdfBuffer = await generateInvoice(invoice);
fs.writeFileSync('invoice.pdf', Buffer.from(pdfBuffer));

Best Practices

1. Use CSS for Styling

Our API supports full CSS, including:

Flexbox and Grid layouts
Custom fonts (via web fonts or base64 embedding)
Media queries for print-specific styles
CSS variables

2. Handle Errors Gracefully

Always check the response status and handle errors:

const response = await fetch('https://api.docapi.co/v1/pdf', {
  // ... options
});
 
if (!response.ok) {
  const error = await response.json();
  console.error('PDF generation failed:', error.message);
  throw new Error(error.message);
}

3. Use Environment Variables

Never hardcode your API key:

const apiKey = process.env.DOCAPI_KEY;
if (!apiKey) {
  throw new Error('DOCAPI_KEY environment variable is required');
}

Next Steps

Start generating PDFs today with Doc API's simple, reliable API.