n8n Workflow: Process Invoice PDFs from Gmail to Zoho Books

Automatically turn Gmail invoice PDFs into deduplicated Zoho Books bills—then archive the originals in Google Drive

This n8n workflow monitors your Gmail for invoice emails with PDF attachments, extracts the invoice data using Parseur, checks for duplicates in Zoho Books, and archives each original PDF into a month-based folder in Google Drive.

What this workflow does

• Polls Gmail every minute for new emails that match the trigger condition (currently has:attachment) and downloads the attached invoice PDF.
• Uploads the PDF to Parseur, waits briefly for processing, and retrieves extracted invoice data as JSON via the Parseur API.
• Prevents duplicate bills in Zoho Books by searching Zoho Books for an existing bill for the configured vendor that matches the extracted invoice number.
• If no match exists, it creates a new Zoho Books bill using the parsed dates and line items; if a match exists, it skips processing as a duplicate.
• Archives the original invoice PDF: downloads the PDF and stores it in a Google Drive folder named YYYY-MM based on the invoice date.
• Creates folders automatically in Google Drive when needed, and uploads the file as {invoice_number}.pdf.

Use cases

• Accounts payable automation: ingest vendor invoices from email attachments and turn them into Zoho Books bills with minimal manual work.
• Duplicate-safe processing: ensure the same invoice number doesn’t generate multiple bills.
• Clean invoice records: keep an auditable archive of original PDFs organized by invoice month.

Technical details

• Gmail polling (checks every minute for messages with attachments and downloads the PDF).
• Parseur integration using n8n-nodes-parseurparseur plus HTTP Request steps to fetch the document and JSON output (using parserId and Parseur API auth headers).
• Zoho Books OAuth2 with configurable organization_id, vendor_id, and account_id for line items.
• Includes workflow logic nodes such as if, wait, merge, and no op.