n8n WhatsApp Booking Workflow w/ Google Calendar & OpenAI

Instant WhatsApp appointment booking—automated with Google Calendar + OpenAI

This n8n workflow turns incoming WhatsApp Booking messages into real calendar events. It uses OpenAI to understand customer intent (book, reschedule, cancel, or ask a question), checks Google Calendar availability to avoid double booking, records results in an n8n Data Table, and escalates unclear cases to Slack.

What this workflow does

• Listens for new WhatsApp messages and normalizes the incoming WhatsApp payload.
• Uses OpenAI to classify intent (book / reschedule / cancel / question / unclear) and extract requested date/time.
• For booking requests: checks Google Calendar availability in the requested window, selects the nearest free slot within business hours, and re-checks the exact slot before creating to prevent double booking.
• Prevents duplicate bookings by looking up an idempotency key (phone number + slot start) in an n8n Data Table. Then it creates the Google Calendar event, reads it back to verify it exists, and stores the booking record.
• Sends WhatsApp confirmations, and can optionally wait until a configured time to send a reminder.
• For reschedules/cancellations: finds the customer’s latest booking in the Data Table, updates or deletes the corresponding Google Calendar event, and confirms the change on WhatsApp.
• For unclear intents or errors: posts an alert with context to a Slack channel for human review (e.g., missing bookings or calendar write/verification issues).

Use cases

• Customers text “Book tomorrow at 3pm” and receive an automatic Google Calendar-confirmed WhatsApp reply.
• “Reschedule to next week” triggers an update of the latest booking and confirmation back to WhatsApp.
• If the request is ambiguous or booking fails verification, your team gets a Slack alert with the details.

Technical details

• Integrations: WhatsApp Business (Busi credentials), Google Calendar, Slack
• AI: OpenAI for intent classification and date/time extraction
• Core logic: if, set, code, switch, wait
• State management: n8n Data Table for idempotency and booking records

Setup: Connect credentials for WhatsApp Busi, then run the workflow to start booking appointments from WhatsApp messages.