Editorial disclosure: I work at Zellbox. Make described from their product page as of August 2026.
Make (formerly Integromat) is the visual automation platform with strong branching + iterator logic. Zellbox layers on top of Google Calendar — anything Make writes there becomes a WhatsApp reminder source via Zellbox.
How it works
- In Make → create a Scenario: any booking source (webhook, HTTP, custom app) → Google Calendar → Create an Event.
- In Zellbox → Onboarding step 2 → connect the destination Google Calendar.
- Every triggered booking now appears on your calendar. Zellbox fires WhatsApp reminders at 24 h and 2 h.
Common recipes
- Webhook (custom booking widget) → Make → GCal → Zellbox WhatsApp reminder
- HTTP call from proprietary practice-management system → Make router → GCal → Zellbox
- Airtable form submission → Make → GCal → Zellbox
What Zellbox adds beyond DIY Make WhatsApp
- Ready template management — Make can call the WhatsApp Business Cloud API directly if you want to author your own templates, but that means owning Meta’s template-approval flow; Zellbox ships approved templates for common appointment patterns so there’s nothing to submit for review.
- Signed consent PDFs on the customer record — the signed PDF attaches automatically as part of the same reminder flow, no separate paperwork step to build in Make.
- Two-way replies land in your Zellbox inbox — when a customer replies to confirm or ask a question, the message shows up next to that customer’s record instead of scattered across a DIY webhook handler.
- BSP relationship handled by Zellbox — a DIY Make setup still needs a Business Solution Provider relationship for the WhatsApp API; Zellbox owns that so there’s no separate BSP contract to negotiate.
Make vs Zapier for this specific flow
When Make’s branching wins
Make’s visual scenario builder handles multi-branch logic (for example, routing different booking sources to different Google Calendars based on service type) more cleanly than Zapier’s linear Zaps, often at a lower cost per operation for high-volume flows.
When to just use Zapier instead
For a single booking source flowing straight into one Google Calendar, Zapier’s simpler trigger-action model is faster to set up. Make earns its complexity once you’re combining more than one booking source or doing conditional routing before the event hits Google Calendar.
Free tier covers 100 reminders/mo.
About the author: Nacho Coll is the founder of Zellbox. He writes about WhatsApp Business automation for appointment-driven small businesses.
