Editorial disclosure: I work at Zellbox. n8n described from their product page as of August 2026.
n8n is the open-source, self-hostable Zapier alternative. Zellbox layers on top of Google Calendar — anything n8n writes there becomes a WhatsApp reminder source.
How it works
- In n8n → create a workflow: any booking source (webhook, HTTP, database trigger) → Google Calendar node → Create 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
- PostgreSQL row inserted → n8n → GCal → Zellbox WhatsApp reminder
- Webhook (from proprietary booking widget) → n8n → GCal → Zellbox
- Airtable → n8n → GCal → Zellbox
What Zellbox adds beyond DIY n8n WhatsApp
n8n can send WhatsApp Business Cloud API messages directly if you want to author the templates + manage the BSP relationship yourself. Zellbox is the ready product with:
- Approved templates for common appointment patterns — no Meta template-approval flow to author or resubmit when wording changes.
- 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 n8n.
- Two-way replies in a shared 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 n8n setup still needs a Business Solution Provider relationship for the WhatsApp API; Zellbox owns that so there’s no separate BSP contract to negotiate.
Self-hosting n8n vs using Zellbox
The fully self-hosted route
n8n’s WhatsApp Business Cloud API node can send messages directly with no third-party product in the loop, which matters for teams that need full data sovereignty or want to avoid any hosted SaaS in the pipeline. It does mean owning template approval and the BSP relationship yourself.
The ready-product route
Zellbox is the alternative for teams that want n8n’s flexible booking-source bridging without also authoring WhatsApp templates or managing a Business Solution Provider relationship — n8n still does the automation; Zellbox just becomes the WhatsApp delivery layer downstream of the Google Calendar event.
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.
