n8n Webhook Booking Validator: Deduplicate Requests

Stop duplicate booking requests—and validate every webhook booking in n8n

This n8n workflow receives booking requests via a webhook, validates and normalizes the incoming fields, enforces lead-time rules, and detects duplicate submissions from the same phone number within 30 minutes—then (for fresh, in-policy requests) creates a booking and returns a confirmation status suitable for WhatsApp/SMS/email.

What this workflow does

• Accepts POST bookings through an n8n Webhook endpoint.
• Validates and normalizes the payload (name, phone, optional email, treatment, preferred time/slot, and optional notes), ensuring required fields are present and formatted as expected.
• Enforces booking policy by calculating how far in the future the requested slot is, then requiring it to be at least 2 hours ahead and no more than 60 days out.
• Handles invalid input safely by logging invalid requests and returning a 422 JSON response with validation errors.
• Declines out-of-policy requests with a 422 JSON response when the requested slot violates the lead-time window.
• Deduplicates by phone number: if the same phone number submits again within 30 minutes, the request is marked as ignored while still returning a success-shaped response.
• Creates a booking and prepares confirmation for valid, non-duplicate requests (placeholder steps), builds a confirmation message, optionally sends it (placeholder), and returns a 200 JSON response with booking status and slot.

Use cases

• Prevent double-bookings when users refresh or resubmit a booking form.
• Ensure appointments only get created for slots that meet your lead-time rules.
• Protect your booking flow from malformed or incomplete webhook requests.
• Streamline confirmation preparation for WhatsApp/SMS/email after booking creation.

Technical details (n8n)

• Webhook to receive POST requests
• if nodes for branching (validation, policy checks, duplicates)
• code node for normalization, lead-time calculation, and duplicate detection logic
• respond to webhook to return 200/422 JSON responses
• Sticky note for workflow guidance