Automatically Detecting Page Numbers and Splitting PDFs into Batches of 10 with n8n + PDF.co

Step 1: Trigger Workflow on Incoming Email

Watch your inbox for new emails with the subject “Multiple Invoices”. When found, it automatically downloads the attached PDF so the workflow can process it.

Node: Email Trigger (IMAP)

• Mailbox Name: INBOX
• Action: Mark as Read
• Download Attachments: True
• Custom Email Rules: ["UNSEEN", ["SUBJECT", "Multiple Invoices "]]

Success: Workflow triggers only when a new Multiple Invoices email with attachments is received.

Step 2: Upload the PDF to PDF.co

Sends the attached PDF file securely to PDF.co. This makes the file available for further processing, like checking page count or splitting.

Node: PDF.co API → Upload File

• Binary Data: true
• Binary Property Name: attachment_0
• Name: ={{ $json.subject }}

Success: Email attachment is uploaded, and PDF.co returns a file URL.

Step 3: Extract Page Count

Uses PDF.co to analyze the uploaded file. It retrieves the total number of pages (PageCount), which is needed to decide if splitting is required.

Node: PDF.co API → PDF Information & Form Fields

• URL: ={{ $json.url }}

Success: PDF.co responds with metadata, including PageCount.

Step 4: Apply Page-Splitting Logic (Custom JS)

A custom JavaScript block checks how many pages the PDF has:

• If less than 10 pages → keep the whole file.
• If 10–14 pages → keep the whole file.
• If 15+ pages → split into batches of 10 pages each.

This ensures only big PDFs get split.

Node: Code

Here’s the logic you used:

// Get PageCount safely
const pageCount = parseInt($json.body.PageCount, 10);

if (isNaN(pageCount) || pageCount <= 0) {
  throw new Error("Invalid or missing PageCount value.");
}

const ranges = [];

// Rule 1: If below 10 pages → keep whole file
if (pageCount < 10) {
  ranges.push(`1-${pageCount}`);
}
// Rule 2: If 15 pages or more → split into 10-page batches
else if (pageCount >= 15) {
  const batchSize = 10;
  for (let start = 1; start <= pageCount; start += batchSize) {
    const end = Math.min(start + batchSize - 1, pageCount);
    ranges.push(`${start}-${end}`);
  }
}
// Rule 3: If between 10 and 14 → keep whole file
else {
  ranges.push(`1-${pageCount}`);
}

return [{
  pages: ranges.join(",")
}];

Success: Produces page ranges like 1-10,11-20,21-30.

Step 5: Split the PDF

Calls PDF.co again with the page ranges from Step 4. PDF.co creates separate files for each range (e.g., 1-10.pdf, 11-20.pdf).

Node: PDF.co API → Split PDF

• URL: ={{ $('Assign URLs to Binary Files').item.json.url }}
• Pages: ={{ $json.pages }}

Success: Returns an array of split file URLs.

Step 6: Flatten the Split URLs

The split step returns all file URLs in one array. This code breaks them into individual items, so each file can be processed one by one.

Node: Code

// Get the array of URLs from the Split PDF output
const urls = $json.body;

if (!Array.isArray(urls)) {
  throw new Error("Expected 'body' to be an array of URLs, got: " + typeof urls);
}

return urls.map(url => ({
  json: { url }
}));

Success: Each split file URL is turned into an individual n8n item.

Step 7: Download Each PDF

For each file URL, the HTTP Request node downloads the PDF. This prepares the binary data so it can be uploaded to Google Drive.

Node: HTTP Request

• Method: GET
• URL: ={{ $json.url }}
• Response Format: File
• Batching: 1 file per request

Success: Downloads each split file individually.

Step 8: Upload to Google Drive

Finally, each file is uploaded individually into your Google Drive folder (not zipped). Each file is named according to the original split part (like Multiple_Invoices_page1-10.pdf).

Node: Google Drive → Upload

• Drive: My Drive
• Folder: OUTPUT1
• Binary Property: data

File Name: {{$json["url"].split("/").pop().split("?")[0]}}

Success: Each split file is uploaded to Drive as a standalone PDF.