Gmail PDF Invoice & PO Extract to XML CSV JSON | n8n

Turn Gmail invoice & PO PDFs into ERP-ready XML, CSV, and JSON automatically

This n8n workflow monitors your Gmail for unread invoice or purchase order PDF attachments, extracts their text, validates key fields and line-item totals, and outputs structured XML, CSV, and JSON files—while alerting a reviewer when something doesn’t match the rules.

What this workflow does

• Polls Gmail every 15 minutes for unread messages matching a configurable PDF invoice/PO search query, then downloads attachments.
• Splits and processes PDF attachments and extracts selectable text from each PDF.
• Detects document type (invoice vs purchase order) and parses header fields such as document numbers, dates, vendor, and currency.
• Parses line items and totals, then performs rule-based validation of required fields.
• Validates calculations by checking line-item math and subtotal/tax/total consistency.
• Flags duplicates using workflow static data to avoid re-processing the same document.
• Outputs structured files for valid documents: generates ERP-style XML, plus CSV and JSON per document.
• Handles exceptions by sending a Gmail message to a reviewer email with validation errors and key extracted values.
• Marks the original Gmail message as read so it won’t be processed again (skipping the built-in sample run).

Use cases

• SaaS operations teams routing invoice/PO PDFs from suppliers directly into downstream ERP formats.
• Automation engineers building a reliable invoice-to-data pipeline with validation and human review for edge cases.
• Finance teams reducing manual copying by converting Gmail PDF invoices/POs into XML/CSV/JSON for ingestion.

Technical details

• Gmail trigger (OAuth2) for polling unread invoice/PO PDFs and actions to mark messages as read.
• Parsing and control flow using if, set, code, filter, and documentation/flow notes via sticky note.

Optional: upload the generated XML/CSV/JSON files to a specified Google Drive folder.