> ## Documentation Index
> Fetch the complete documentation index at: https://docs.zapfy.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> Zapfy's WhatsApp API — send and receive messages through a single surface, no matter how it connects to WhatsApp.

Zapfy is a multi-tenant WhatsApp API. You talk to **one contract** — how Zapfy
connects to WhatsApp (unofficial or the official Cloud API) stays abstracted
behind the gateway.

## How it works

* **Outbound** — you call Zapfy's REST API to send messages.
* **Inbound** — Zapfy delivers your instance's events (incoming messages, delivery
  status, connection) to the **webhooks** you register.

Each **instance** represents one WhatsApp number. You register the instance in the
dashboard, connect the number, and start sending/receiving via the API.

## Authentication

Every call uses a token in the `Authorization` header:

```bash theme={null}
Authorization: Bearer zpfy_inst_xxxxxxxxxxxx
```

The token is generated when the instance is created and is available in the dashboard.

<Card title="Configure webhooks" href="/en/webhooks/configuration" icon="webhook">
  Receive your instance's events: one URL, many events.
</Card>