Validate supplier invoices against stock and raise purchase orders with n8n

In a review of eight months with n8n, the dev.to writer nova_gg describes an invoice workflow built for a client in Dubai. It watches the client's Gmail for invoice emails, sends PDF attachments to an OpenAI vision model to pull out vendor, amount, items and dates, and compares them with an inventory sheet in Google Sheets. When things match and amounts look sensible, it creates a purchase order in the ERP, alerts purchasing on Slack and confirms receipt to the sender. The 23 node flow took three days, mostly spent on edge cases. The client handles 40 to 50 invoices weekly; about 90% now go through automatically, saving eight to ten hours a week.