# How to build an appointment booking and reminder chatbot > An appointment flow fetches real availability through a webhook, books the chosen slot and saves the date to a contact field. A campaign based on that date then sends reminders that let customers confirm, reschedule or cancel in one tap. URL: https://on-chat.live/guides/appointment-booking-chatbot/ Last updated: 2026-10-27 Phone calls to book appointments tie up your front desk, and missed appointments cost you slots that someone else could have used. A booking flow on WhatsApp or SMS solves both: customers book in a few taps, and automatic reminders let them confirm or reschedule before the day. This guide builds two connected pieces in On-chat's [flow builder](https://on-chat.live/flow-builder/): 1. a **booking flow** that offers real available slots, and 2. a **reminder campaign** that runs automatically before each appointment. ## How the pieces fit together The booking flow and the reminder campaign are connected by one contact field that holds the appointment date. The flow writes the date when a customer books, and the campaign reads it to schedule reminders. ``` Booking flow: Choose service → Get free slots (webhook) → Pick a slot → Confirm (webhook) → Save date to contact Reminder campaign: 1 day before appointment → Confirm / Reschedule / Cancel 2 hours before → Short reminder ``` The key link is a **contact field** holding the appointment date. The booking flow writes it, and the campaign reads it. ## Step 1: Create the appointment date field Create a contact field of type **date**, for example `appointment_date`. A campaign can only schedule events relative to a date field, so this is essential. You may also want `appointment_service` (text) and `appointment_id` (text) to store details from your booking system. ## Step 2: Ask which service Start the booking flow with **Send the contact a message**: > Hi @contact.first_name! What would you like to book? Quick replies: `Consultation`, `Follow-up`, `Cleaning`. Then **Wait for the contact to respond** and save the result as `service`. ## Step 3: Fetch real availability with a webhook Add **Call a webhook** to ask your calendar or booking system for open slots: - **Method:** `GET` - **URL:** `https://api.your-clinic.com/slots?service=@results.service.category` Return a short list your flow can show directly, for example: ```json { "slots": [ { "id": "s1", "label": "Tue 4 Nov, 10:00", "start": "2026-11-04T10:00:00+02:00" }, { "id": "s2", "label": "Tue 4 Nov, 15:30", "start": "2026-11-04T15:30:00+02:00" }, { "id": "s3", "label": "Wed 5 Nov, 11:00", "start": "2026-11-05T11:00:00+02:00" } ] } ``` Then send the options, using the response in the quick replies: > Here are the next available times: Quick replies: `@(webhook.slots[0].label)`, `@(webhook.slots[1].label)`, `@(webhook.slots[2].label)` Keep it to three options. If none suit, add a fourth quick reply, `Other time`, that opens a ticket so the front desk can help. > Don't have a booking API? Start simpler: offer fixed choices like `Morning` / `Afternoon` and open a ticket for staff to confirm the exact time. You can add the webhook later without changing the rest of the flow. ## Step 4: Confirm the booking After the customer picks a slot, **Call a webhook** again with `POST` to reserve it in your system: ```json { "phone": "@contact.urn", "name": "@contact.name", "service": "@results.service.category", "slot": "@results.slot" } ``` Have your API return the confirmed start time and a booking ID. On **Success**: 1. **Update the contact**: set `appointment_date` to the returned start time and `appointment_id` to the booking ID. 2. Send a confirmation: > You're booked for @results.slot ✅ Reply CHANGE any time if you need to reschedule. On **Failure** (for example, someone else took the slot a second earlier), apologise and loop back to fetch fresh availability. ## Step 5: Set up the reminder campaign Now the part that cuts no-shows. Go to **Campaigns**: 1. Create a campaign based on a group, for example `Patients` (make sure the booking flow adds contacts to this group). 2. Add an event **1 day before** `appointment_date` that starts a short **reminder flow**. 3. Add a second event **2 hours before** that sends a brief message. Because events are relative to each contact's own date, every customer gets reminders at the right time, and if the date changes the reminders move with it. ## Step 6: Build the reminder flow The 1-day reminder should make the next action one tap away: > Reminder: your @fields.appointment_service is tomorrow at @(format_datetime(fields.appointment_date, "tt:mm")). Can you make it? Quick replies: `Yes, see you`, `Reschedule`, `Cancel`. - **Yes**: thank them, and optionally **Call a webhook** to mark the appointment confirmed. - **Reschedule**: **Enter another flow** and send them back into the booking flow, starting at the availability step. - **Cancel**: call your API to free the slot, then ask (optionally) why. That data is gold. On WhatsApp, a reminder sent more than 24 hours after the customer's last message must use an **approved message template**. Create a utility template for reminders and use it for the first message of the reminder flow. ## Step 7: Reach everyone Not every customer uses WhatsApp. Flows run on any channel, so: - send the same reminder over **SMS** to contacts without WhatsApp, - or use a [voice flow](https://on-chat.live/ivr-voice-automation/) that calls and asks the customer to press 1 to confirm or 2 to reschedule. ## Test before launch Test the booking flow, the saved date and the reminder campaign together before real customers use them. 1. Book through the **Simulator** and check the date lands in `appointment_date`. 2. Set a test appointment for tomorrow and confirm the campaign event is scheduled. 3. Try **Reschedule** and **Cancel** to make sure your booking system updates. ## What to track Track how many customers confirm, reschedule or cancel, and compare no-shows before and after launch. - **Confirmation rate** from the reminder flow results. - **Reschedules versus cancellations**: a reschedule is a saved appointment. - **No-shows** before and after launch, from your own booking system. For clinics, see how this fits into [patient messaging for healthcare](https://on-chat.live/solutions/healthcare/). To go deeper on live data, read [making your chatbot dynamic with webhooks](https://on-chat.live/guides/dynamic-chatbot-webhooks/), or [start building for free](https://on-chat.live/org/signup/). ## Put this guide into practice - [Visual flow builder](https://on-chat.live/flow-builder/): Build dynamic conversation flows without code: branch on answers, use live data from your systems and run one flow on WhatsApp, SMS and voice. - [Healthcare](https://on-chat.live/solutions/healthcare/): Reduce no-shows with automated appointment reminders on SMS, WhatsApp and voice. Confirm, reschedule and follow up with patients automatically. ## Keep reading - [How to Build a WhatsApp Chatbot Without Code](https://on-chat.live/guides/how-to-build-a-whatsapp-chatbot/): A step-by-step tutorial for building a dynamic WhatsApp chatbot in a visual flow builder, from your first message to live data and agent handoff. - [Chatbot Flow Design: 12 Best Practices](https://on-chat.live/guides/chatbot-flow-design-best-practices/): Practical rules for designing chatbot conversation flows that customers finish: branching, fallbacks, personalisation, handoff and testing. - [Make Your Chatbot Dynamic with Webhooks](https://on-chat.live/guides/dynamic-chatbot-webhooks/): Connect your chatbot flows to live data. Learn how webhooks, expressions and splits turn a scripted bot into one that answers with real information.