Automating PDF Generation with n8n

n8n is a powerful workflow automation tool that allows you to connect docpenny to hundreds of other services without writing code. This guide will show you how to set up a robust workflow to generate and handle PDFs.

What do I need before starting?

• An n8n instance (cloud or self-hosted).
• A docpenny API Key.
• A Template ID.

1. Triggering the Generation

The first step is to send your data to docpenny using the HTTP Request node.

Configure the Node:

• Method: POST
• URL: https://api.docpenny.com/api/jobs
• Authentication: Header Auth
  • Name: x-api-key
  • Value: Your API Key
• Send Body: true
• Body Content Type: JSON
• Specify Body: Using Fields Below or JSON
  • templateId: Your Template ID
  • data: A JSONL string of your data (e.g., {"name": "Alice"})

How do I handle async job processing?

Since docpenny generates documents asynchronously to ensure reliability, you need to wait for the job to complete.

The “Wait & Check” Pattern:

1. Wait Node: Add a Wait node after your request, set to wait for 5-10 seconds.
2. HTTP Request (Check Status):
   • Method: GET
   • URL: https://api.docpenny.com/api/jobs/{{ $node["HTTP Request"].json["jobId"] }}
   • Authentication: Use the same Header Auth as before.
3. IF Node: Check if {{ $node["Check Status"].json["status"] }} is all_tasks_downloaded, ready_full_zip, or ready_partial_zip.
   • False: Loop back to the Wait node.
   • True: Proceed to download.

How do I download the generated PDF?

Once the job is complete, use another HTTP Request node to download the ZIP file.

Configure the Node:

• Method: GET
  • URL: https://api.docpenny.com/api/download/zip/{{ $node["HTTP Request"].json["jobId"] }}
• Response Format: File

Note: The ZIP download is one-time only. After downloading, subsequent requests to the same URL will return a 404.

You can then pass this file to other nodes, such as Email (SendGrid/Gmail), Google Drive, or Slack.

Pro Tip: Using Webhooks

Instead of polling with Wait nodes, you can use n8n’s Webhook node as a “Wait for Webhook” trigger.

1. In your initial POST /jobs request, include a webhookUrl pointing to your n8n Webhook URL.
2. Your workflow will then be triggered automatically as soon as the PDF is ready, saving execution time and resources.

How do I secure webhook calls?

Security is critical when using public webhooks. docpenny signs every payload with an X-Webhook-Signature header.

Verifying in n8n:

You can use a Crypto node or a Code node to verify the signature:

1. Code Node: After the Webhook trigger, add a Code node.

2. Implementation:

   const crypto = require('crypto');
   const secret = 'your_webhook_secret';
   const signature = $node["Webhook"].json.headers['x-webhook-signature'];
   const body = JSON.stringify($node["Webhook"].json.body);
   
   const hmac = crypto.createHmac('sha256', secret);
   const digest = 'sha256=' + hmac.update(body).digest('hex');
   
   if (signature !== digest) {
       throw new Error('Invalid Webhook Signature');
   }
   
   return $node["Webhook"].json;

Official Blueprint

To get started instantly, you can download our pre-built n8n blueprint: