{"product_id":"n8n-workflow-backfill-cancelled-slots-w-google-calendar-whatsapp","title":"n8n Workflow: Backfill Cancelled Slots w\/ Google Calendar \u0026 WhatsApp","description":"\u003ch3\u003eBackfill cancelled appointment slots automatically with Google Calendar + WhatsApp\u003c\/h3\u003e\n\u003cp\u003eThis n8n workflow checks your \u003cstrong\u003eGoogle Calendar\u003c\/strong\u003e every 15 minutes for cancelled or deleted appointments, finds the matching \u003cstrong\u003efreed slots\u003c\/strong\u003e in your Google Sheet, and sends a WhatsApp offer to the right person from your \u003cstrong\u003eWaitlist\u003c\/strong\u003e—so empty spaces don’t cost you revenue.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRuns on a 15-minute schedule\u003c\/strong\u003e to stay responsive without constant manual work.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReads appointment events from Google Calendar\u003c\/strong\u003e within your lookahead window (including \u003cem\u003edeleted events\u003c\/em\u003e).\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLoads Bookings and Waitlist tabs\u003c\/strong\u003e from the same Google Sheet (same spreadsheet, consistent data model).\u003c\/li\u003e\n  \u003cli\u003eMarks an appointment row as a \u003cstrong\u003efreed slot\u003c\/strong\u003e if the event was cancelled\/deleted or if the booking is marked \u003cstrong\u003eno-show\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003eExcludes slots that start \u003cstrong\u003einside your minimum notice window\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eMatches freed slots to the first eligible waitlist member\u003c\/strong\u003e (joining order) who requested the relevant \u003cstrong\u003eservice\u003c\/strong\u003e and \u003cstrong\u003epractitioner\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eWhatsApp sending is controlled by a switch:\u003c\/strong\u003e when \u003cem\u003esendOffers\u003c\/em\u003e is on, offers are sent; when off, the workflow stops at a dry-run step and nothing goes out.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eLogs every sent offer\u003c\/strong\u003e by appending details (slot + person info) to the \u003cstrong\u003eOffer log\u003c\/strong\u003e tab.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eAn appointment is cancelled at the last minute—this workflow immediately notifies the next eligible waitlist customer via \u003cstrong\u003eWhatsApp\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003eA “no-show” is recorded in your Bookings tab—freed capacity is offered to the earliest matching waitlist entry.\u003c\/li\u003e\n  \u003cli\u003eYou want a safe rollout: run with \u003cem\u003esendOffers\u003c\/em\u003e off to verify matching and logging before enabling WhatsApp delivery.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eIntegrations:\u003c\/strong\u003e Google Calendar, Google Sheets, WhatsApp Business Cloud.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003en8n nodes\/logic:\u003c\/strong\u003e schedule trigger, \u003cstrong\u003eif\u003c\/strong\u003e, \u003cstrong\u003eset\u003c\/strong\u003e, \u003cstrong\u003ecode\u003c\/strong\u003e, \u003cstrong\u003eno op\u003c\/strong\u003e, \u003cstrong\u003esplit out\u003c\/strong\u003e, and \u003cstrong\u003ewhats app\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSetup required:\u003c\/strong\u003e provide calendar ID + spreadsheet ID in Settings; create spreadsheet tabs named \u003cstrong\u003eBookings\u003c\/strong\u003e, \u003cstrong\u003eWaitlist\u003c\/strong\u003e, and \u003cstrong\u003eOffer log\u003c\/strong\u003e; store waitlist phone numbers with \u003cstrong\u003ecountry code\u003c\/strong\u003e; add WhatsApp Business Cloud credentials and phone number ID.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003cp\u003e\u003cstrong\u003ePerfect for n8n users, automation engineers, and SaaS operators\u003c\/strong\u003e running appointment businesses who need reliable, data-driven backfilling of cancelled slots—without manual outreach.\u003c\/p\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":46029396213939,"sku":"N8N-19598","price":46.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/ZY82PnC6C8BebF6hqaQHn_i3sEugYz.png?v=1789463474","url":"https:\/\/buyflowscripts.com\/products\/n8n-workflow-backfill-cancelled-slots-w-google-calendar-whatsapp","provider":"N8N Commerce","version":"1.0","type":"link"}