Extract and organize Colombian invoices with Gmail, GPT-4o & Google Workspace

🧾 Personal Invoice Processor

This N8N workflow automates the extraction and organization of personal invoices in Colombia received via Gmail. It includes the following key steps:

🔁 Flow Summary

1. Email Trigger - Polls Gmail every 30 minutes for emails with .zip attachments (assumed to contain invoices). - Expects ZIP file following DIAN standards.

2. ZIP File Handling - Extracts all files. - Filters only PDF and XML files for processing.

3. Data Extraction & Processing - Uses LangChain Agent + OpenAI (GPT-4o-mini) to extract: - Tipo de documento (Factura / Nota Crédito) - Número de factura - Fecha de emisión (YYYY-MM-DD) - NIT emisor y receptor (sin dígito de verificación) - Razón social del emisor - Subtotal, IVA, Total - CUFE - Resumen de compra (max 20 words, formatted sentence)

4. Validation - Ensures Total = Subtotal + IVA using a calculator node.

5. Storage - Uploads the original PDF to Google Drive. - Renames the file to: YYYY-MM-DD-NUMEROFACTURA.pdf. - Inserts or updates invoice details in Google Sheets using a unique Key (NITEmisor + NumeroFactura) to prevent duplication.