Confirm Webhook Appointments in Google Calendar (n8n)

Automatically confirm booking requests in Google Calendar — with clear webhook outcomes

This n8n workflow receives confirmed appointment requests via a webhook, checks availability in Google Calendar, and creates a private calendar event when the time slot is valid. It returns precise HTTP responses for invalid input, busy intervals, and provider failures—so your booking pipeline stays reliable.

What this workflow does

• Receives a POST webhook request containing: start, end, summary, request_id, and confirmed.
• Validates the request by ensuring:
  • confirmed is true
  • timestamps use RFC3339 format with seconds and an explicit offset
  • the start time is in the future
  • the appointment duration is max 1 day
  • request_id matches the required format
• Checks Google Calendar availability for the requested start/end interval.
• Handles provider uncertainty: returns 502 if availability cannot be confirmed.
• Creates a private Google Calendar event using summary and uses request_id as the event ID when available.
• Verifies creation by confirming the returned event ID, confirmed status, and the requested time range.
  • 400 for invalid input
  • 409 if the interval is busy
  • 502 if creation is unconfirmed or provider failure occurs
  • 201 on successful verification

Use cases

• Turn confirmed booking requests from your app into private Google Calendar events.
• Coordinate scheduling across systems using request_id as a stable event identifier.
• Give your frontend or backend deterministic responses (201/400/409/502) for booking status handling.

Technical details

• Nodes/technology: webhook, respond to webhook, if, code (plus sticky note documentation)
• Integrations: Google Calendar via OAuth2 (set your target calendar ID)
• Workflow behavior: validates webhook payload, checks availability, creates private events, verifies event details, returns HTTP outcomes