Automating Invoice Image Collection, PDF Conversion, and Archiving in Google Drive with n8n + PDF.co

Step 1: Trigger Document Collection Processing

Node: Email Trigger (IMAP)

Settings:

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

Success Looks Like: The workflow is triggered when a new or unread email with the subject “Invoice Package” arrives, and attachments are pulled into the workflow.

Step 2: Normalize Attachments into Workflow Items

Node: Code (JavaScript)

Settings: Use the provided JavaScript code to process each attachment and extract metadata (filename, type, etc.). This ensures invoices are properly structured for PDF.co. (Download sample JavaScript code here.)

Success Looks Like: Each document is transformed into a structured workflow item, ready for upload.

Step 3: Upload Documents to PDF.co

Node: PDF.co API → Upload File

Settings:

• Binary File: True
• Input Binary Field: file

Success Looks Like: All invoice image attachments are uploaded to PDF.co, returning secure file URLs for further processing.

Step 4: Collect Uploaded File URLs

Node: Code (JavaScript)

Settings: Use a collector function after upload to gather all returned URLs into a single files array JSON object that PDF.co’s Merge endpoint expects. (Download sample collector code here.)

Success Looks Like: All invoice image URLs are collected and formatted in the correct array structure for merging.

Step 5: Combine All Documents into One PDF

Node: PDF.co API → Merge PDF

Settings:

Input Links: Map the ordered URLs array

={{ $json.urls[0] }}

={{ $json.urls[1] }}

={{ $json.urls[2] }}

={{ $json.urls[3] }}

Success Looks Like: All uploaded invoice images are merged into a single clean PDF document.

Step 6: Download Final PDF

Node: HTTP Request

Settings:

• Method: GET
• URL: {{ $json.url }} (from PDF.co output)
• Authentication: None

Success Looks Like: The merged PDF is downloaded as binary data, ready to be stored.

Step 7: Save Completed Package to Google Drive

Node: Google Drive → Upload

Settings:

• Input Data Field Name: data
• Parent Drive: My Drive
• Parent Folder: OUTPUT1

Success Looks Like: The final PDF appears neatly in your designated Google Drive folder