{"product_id":"invoice-processing-workflow-gmail-pdfs-to-sheets-slack","title":"Invoice Processing Workflow: Gmail PDFs to Sheets \u0026 Slack","description":"\u003ch3\u003eTurn Gmail PDF invoices into organized Sheets records—and Slack alerts—in minutes\u003c\/h3\u003e\n\u003cp\u003eThis n8n \u003cstrong\u003eInvoice Processing Workflow: Gmail PDFs to Sheets \u0026amp; Slack\u003c\/strong\u003e automatically captures PDF invoices from \u003cstrong\u003eGmail\u003c\/strong\u003e or an \u003cstrong\u003en8n upload form\u003c\/strong\u003e, extracts invoice fields with \u003cstrong\u003eOpenAI (GPT-4o-mini)\u003c\/strong\u003e, de-duplicates entries, files PDFs in \u003cstrong\u003eGoogle Drive\u003c\/strong\u003e, logs them in \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e, and notifies your \u003cstrong\u003eSlack\u003c\/strong\u003e channel—with an optional finance review email for anything that needs attention.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eTriggers on new PDFs\u003c\/strong\u003e when a Gmail email arrives with a PDF attachment or when you upload one or more PDF invoices via an n8n form.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSplits and filters binaries\u003c\/strong\u003e so each PDF becomes a single item, while non-PDF files are ignored.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExtracts invoice data using OpenAI\u003c\/strong\u003e: text is sent to \u003cstrong\u003eGPT-4o-mini\u003c\/strong\u003e, which returns \u003cstrong\u003estrict JSON\u003c\/strong\u003e invoice fields.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eValidates and normalizes\u003c\/strong\u003e dates and number formats, checks totals (net + tax vs total), and flags inconsistent or missing data as \u003cstrong\u003e“Needs review.”\u003c\/strong\u003e\n\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eDe-duplicates with Google Sheets\u003c\/strong\u003e by looking up the invoice number in the “Invoices” tracker and marking matches as duplicates.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eFiles and records\u003c\/strong\u003e: duplicates are posted to Slack as “skipped”; non-duplicates upload the PDF to \u003cstrong\u003eGoogle Drive\u003c\/strong\u003e, append a new row (including the Drive link) to \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e, and notify Slack.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRoutes finance review\u003c\/strong\u003e: if the appended invoice is \u003cstrong\u003e“Needs review,”\u003c\/strong\u003e it sends a \u003cstrong\u003eGmail\u003c\/strong\u003e message to finance with validation notes and the Drive link.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWeekly digest\u003c\/strong\u003e: every Monday at \u003cstrong\u003e08:00\u003c\/strong\u003e, it reads the tracker, builds a summary (booked last 7 days, due in 7 days, review backlog), and posts it to Slack.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eSaaS operators who receive vendor invoices via email and want a clean, auditable invoice ledger.\u003c\/li\u003e\n  \u003cli\u003eAccounting teams who need automatic “Needs review” flags and a weekly backlog digest in Slack.\u003c\/li\u003e\n  \u003cli\u003eAutomation engineers building invoice processing pipelines with de-duplication and Drive\/Sheets logging.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations\/Nodes:\u003c\/strong\u003e Gmail, Google Sheets, Google Drive, Slack, OpenAI (GPT-4o-mini)\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eCore logic:\u003c\/strong\u003e splitting\/filtering PDF binaries, OpenAI JSON extraction, normalization + totals checks, de-duplication, conditional routing (includes “Needs review”).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eUtility nodes mentioned:\u003c\/strong\u003e if, code, filter, sticky note.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":45837436059827,"sku":"N8N-18277","price":37.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/4-Ih9sfHSTE5zkMjXjfvu_U795IUXB.png?v=1786794173","url":"https:\/\/buyflowscripts.com\/products\/invoice-processing-workflow-gmail-pdfs-to-sheets-slack","provider":"N8N Commerce","version":"1.0","type":"link"}