{"product_id":"fill-cancelled-booking-slots-via-waitlist-webhooks-sms-whatsapp","title":"Fill Cancelled Booking Slots via Waitlist Webhooks + SMS\/WhatsApp","description":"\u003ch3\u003eInstantly fill cancelled booking slots using waitlist webhooks (SMS\/WhatsApp ready)\u003c\/h3\u003e\n\u003cp\u003eWhen a booking is cancelled, this n8n workflow automatically finds the best waitlist matches, sends offers immediately, and uses atomic “first reply wins” claim handling—then sweeps every 30 minutes to re-offer expired\/declined slots until the waitlist runs out.\u003c\/p\u003e\n\n\u003ch3\u003eWhat this workflow does\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003eReceives cancelled slots via webhook:\u003c\/strong\u003e Your calendar system POSTs each freed slot to the first webhook URL. Invalid payloads are rejected cleanly with a \u003cstrong\u003e422\u003c\/strong\u003e response.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRanks the waitlist for that exact slot:\u003c\/strong\u003e Treatment match counts most, then flexibility, then the person’s own priority score. The \u003cstrong\u003etop three\u003c\/strong\u003e matches get offer messages at once.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRecords an “offer book”:\u003c\/strong\u003e Each offer round tracks who was offered, who declined, and when the round expires.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eClaims are handled atomically:\u003c\/strong\u003e Replies arrive at a second webhook. The claim guard ensures the \u003cstrong\u003efirst TAKE wins\u003c\/strong\u003e the slot; later takers receive a polite response. \u003cstrong\u003eSTOP\u003c\/strong\u003e marks the sender as declined and releases the slot immediately.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eRe-offers automatically with a 30-minute sweeper:\u003c\/strong\u003e Every 30 minutes, a sweeper finds expired or declined slots, excludes anyone already offered\/declined, re-ranks remaining candidates, and sends the next offers. When the waitlist is empty, the slot closes as \u003cstrong\u003eexhausted\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eSchedules itself:\u003c\/strong\u003e Runs on a \u003cstrong\u003e30-minute schedule\u003c\/strong\u003e and logs a summary of re-offered and exhausted slots.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eUse cases\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003eReduce revenue loss when clients cancel last-minute by filling the gap from a waitlist.\u003c\/li\u003e\n  \u003cli\u003eHandle high-volume cancellations safely with “first reply wins” atomic claim logic.\u003c\/li\u003e\n  \u003cli\u003eKeep messaging consistent by routing offers through your messaging webhook for SMS\/WhatsApp delivery.\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eTechnical details (n8n)\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003e\n\u003cstrong\u003ewebhook\u003c\/strong\u003e nodes for: cancelled-slot intake and claim-reply processing\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eif\u003c\/strong\u003e and \u003cstrong\u003ecode\u003c\/strong\u003e nodes for payload validation, ranking, and atomic claim behavior\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003eschedule trigger\u003c\/strong\u003e for the 30-minute sweeper\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003erespond to webhook\u003c\/strong\u003e for immediate \u003cstrong\u003e422\u003c\/strong\u003e rejections and reply outcomes\u003c\/li\u003e\n  \u003cli\u003e\n\u003cstrong\u003esticky note\u003c\/strong\u003e nodes for workflow clarity\/documentation\u003c\/li\u003e\n\u003c\/ul\u003e\n\n\u003ch3\u003eSetup\u003c\/h3\u003e\n\u003cul\u003e\n  \u003cli\u003ePoint your booking system cancellation event to the \u003cstrong\u003efirst webhook URL\u003c\/strong\u003e.\u003c\/li\u003e\n  \u003cli\u003ePoint your messaging webhook (SMS\/WhatsApp sending) to the \u003cstrong\u003eclaim reply URL\u003c\/strong\u003e.\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"N8N Commerce","offers":[{"title":"Default Title","offer_id":46217929162931,"sku":"N8N-20805","price":57.99,"currency_code":"GBP","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0749\/6279\/6723\/files\/ToIr0NgiveJ7mUQKSuKIo_Cei0cY8a.png?v=1791883676","url":"https:\/\/buyflowscripts.com\/products\/fill-cancelled-booking-slots-via-waitlist-webhooks-sms-whatsapp","provider":"N8N Commerce","version":"1.0","type":"link"}