{"product_id":"approve-vendor-invoices-from-gmail-with-claude-sheets-slack","title":"Approve Vendor Invoices from Gmail with Claude, Sheets \u0026 Slack","description":"\u003ch3\u003eApprove vendor invoices from Gmail in minutes—using Claude, Google Sheets, and Slack\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow automatically reads PDF vendor invoices arriving in \u003cstrong\u003eGmail\u003c\/strong\u003e, validates them against your \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e rules, and either \u003cstrong\u003eauto-approves\u003c\/strong\u003e them or sends an approval request to \u003cstrong\u003eSlack\u003c\/strong\u003e—with every decision logged for audit-ready traceability.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMonitors Gmail for invoice emails\u003c\/strong\u003e: Triggers every minute when a message arrives with a PDF attachment, running a separate execution per invoice email.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eExtracts structured invoice data with Claude\u003c\/strong\u003e: Sends the attached PDF (plus email context) to the \u003cstrong\u003eAnthropic Messages API\u003c\/strong\u003e to extract vendor, invoice number, dates, totals, PO number, and bank details.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eChecks Vendors, Purchase Orders, and invoice log entries\u003c\/strong\u003e: Loads the \u003cstrong\u003eVendors\u003c\/strong\u003e, \u003cstrong\u003ePurchase orders\u003c\/strong\u003e, and \u003cstrong\u003eInvoice log\u003c\/strong\u003e tabs from Google Sheets and verifies vendor status, sender domain, bank-detail matches, arithmetic consistency, duplicates, and PO validity\/tolerance.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eAuto-approves or routes to approvers\u003c\/strong\u003e: Invoices passing all checks, matching an open PO, and staying under your configured auto-approve limit are approved automatically. Anything else is routed for approval—or held if blocking issues are found.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRequests approval in Slack\u003c\/strong\u003e: Sends a Slack DM to the designated approver (and optionally a second approver above the threshold) with a time limit for response.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLogs outcomes in Google Sheets\u003c\/strong\u003e: Writes the final decision and reasons to the \u003cstrong\u003eInvoice log\u003c\/strong\u003e, and posts a status summary to a configured \u003cstrong\u003eSlack\u003c\/strong\u003e channel.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eAP teams that want faster approvals while preventing PO mismatches and duplicate invoices.\u003c\/li\u003e\n  \u003cli\u003eSaaS operators needing audit-friendly invoice decision logs without manual spreadsheet updates.\u003c\/li\u003e\n  \u003cli\u003eAutomation engineers implementing controlled, rules-based invoice processing using n8n.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003en8n nodes\/logic\u003c\/strong\u003e: if, set, code, slack, switch, sticky note.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations\u003c\/strong\u003e: Gmail (PDF invoice trigger), \u003cstrong\u003eAnthropic Messages API\u003c\/strong\u003e (Claude extraction), \u003cstrong\u003eGoogle Sheets\u003c\/strong\u003e (Vendors, Purchase orders, Invoice log), \u003cstrong\u003eSlack\u003c\/strong\u003e (approval DM + channel summary).\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSetup\u003c\/h3\u003e\n\u003cp\u003eCreate a Google Sheets document with tabs named \u003cstrong\u003eVendors\u003c\/strong\u003e, \u003cstrong\u003ePurchase orders\u003c\/strong\u003e, and \u003cstrong\u003eInvoice log\u003c\/strong\u003e, and add the expected columns for your vendor reconciliation and approval workflow.\u003c\/p\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":46146368569523,"sku":"N8N-20234","price":5.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/ejqWalfZqUY9RxG-BjGIY_9v71J7J4.png?v=1790846365","url":"https:\/\/buyflowscripts.com\/products\/approve-vendor-invoices-from-gmail-with-claude-sheets-slack","provider":"N8N Commerce","version":"1.0","type":"link"}