WhatsApp Appointment Booking n8n Workflow w/ OpenAI & Google Calendar

Turn WhatsApp messages into confirmed appointments—automatically (with real Google Calendar checks)

This WhatsApp Appointment Booking n8n Workflow w/ OpenAI & Google Calendar listens for customers messaging your WhatsApp Business number, interprets whether they want to book, reschedule, or cancel, verifies availability on your Google Calendar, and confirms the result back on WhatsApp. If anything is unclear, it escalates to Slack instead of guessing.

What this workflow does

• Trigger: Starts only when someone sends a message to your WhatsApp Business Cloud number.
• Extract & classify intent: Cuts the payload down to phone, name, and message text, then uses OpenAI to determine whether the customer wants to book, move (reschedule), cancel, ask a plain question, or is not confidently classifiable.
• Parse requested date/time: Pulls any date or time mentioned from the message.
• Verify availability before booking: For new bookings, reads your Google Calendar across the requested window, finds the nearest free slot inside your business hours, and re-checks the exact slot right before creating the event.
• Prevent duplicate bookings: Looks up an idempotency key in a Data Table so the same WhatsApp message can’t create multiple events.
• Write & prove: Creates the calendar event, then reads it back to confirm the write succeeded.
• Reschedule/cancel safely: Finds the customer’s latest booking by phone number, acts using the real event id, and confirms changes on WhatsApp.
• Human escalation: Any unclear intent, unverified booking, or reschedule without something to change goes to Slack for review.

Use cases

• A customer texts “Book me next Tuesday at 3” and receives a confirmed slot on WhatsApp.
• A customer asks to “move my appointment” and the workflow updates the correct event id.
• A question like “How much do you charge?” is routed to Slack instead of misinterpreted.
• A busy schedule message is handled by finding the nearest free slot within business hours.

Technical details

• Integrations: WhatsApp Business Cloud (trigger), Google Calendar, OpenAI, Slack.
• n8n nodes/logic used: if, set, code, wait, slack, switch.
• Reminder behavior: Appointment reminders exist as an option, but they are shipped switched off.
• Setup requirement: Connect four credentials including WhatsApp Business Cloud for the trigger.