WhatsApp

Send template messages, broadcasts, flows and replies on WhatsApp from a connected WhatsApp Business Account (platform value whatsapp). A conversation starts with POST /v1/inbox/conversations and a template; a broadcast starts with POST /v1/broadcasts. The same account serves the inbox, group chats, voice calling and Click-to-WhatsApp attribution.

Quick reference

Before you start

WhatsApp requires a WhatsApp Business Account (WABA) inside a Meta Business account (business.facebook.com); a personal WhatsApp account cannot be connected. The WABA is created during the connection flow if you do not have one, and it needs at least one phone number registered to it.

Two rules shape every send. You can message a customer freely for 24 hours after their last message; outside that window the message must be an approved template (Templates). A freshly connected number starts on Meta's lowest messaging tier, 250 unique contacts per day, and Meta raises it as you build messaging history and keep quality up.

Connect

Call GET /v1/connect/whatsapp with profileId and redirect_url. Embedded Signup is the only browser route onto Meta's Cloud API; the coexistence variant adds a QR code the business scans with the WhatsApp Business app (coexistence).

import Zernio from '@zernio/node';

const zernio = new Zernio();

const { data: connect } = await zernio.connect.getConnectUrl({
  path: { platform: 'whatsapp' },
  query: {
    profileId: '66a1f0c2a4b9d3e8f1a2b3c4',
    redirect_url: 'https://myapp.com/callback',
    onboarding: 'api'
  }
});

console.log(connect.authUrl);

Response (200):

{
  "authUrl": "https://www.facebook.com/v21.0/dialog/oauth?client_id=...",
  "state": "..."
}

Send the user to authUrl. They land back on redirect_url with accountId, the id every WhatsApp call takes from here on.

Three questions decide how you connect, and the connection guide answers each with the call to make:

• Whose number. A number you buy through Zernio can also carry Calls and SMS and can only be connected on the profile it was bought for. A number you already own connects through Embedded Signup or with a Meta System User token.
• Coexistence or Cloud API only. Keeping the number in the WhatsApp Business app (coexistence) caps throughput at 20 messages per second and turns off the Groups API and calling. Pass onboarding=api to skip it.
• One number per profile. Each profile holds exactly one WhatsApp number; connect a second number to a second profile.

Who bills what

WhatsApp has two billers, Zernio and Meta. Pricing & costs says which charge lands on which invoice; WhatsApp rates has Meta's numbers by country.

In this section

Analytics

WhatsApp exposes no post-level analytics through its API. Delivery status (sent, delivered, read) is tracked per message and per broadcast recipient, and arrives as the message.delivered and message.read events (inbox webhooks).

Common errors

The connect call fails on a 404 when profileId is unknown, and on a 402 when the team has no payment method (connecting accounts). The conflicts that matter for WhatsApp appear later, when the user picks a number: they come back on your redirect_url as error=one_whatsapp_per_profile, whatsapp_number_pinned_to_profile or whatsapp_number_already_connected, each with its fix in connection and setup.

Related

• Connecting accounts: the redirect flow, headless mode and scopes shared by every platform.
• Messages: the inbox API reference.
• Broadcasts and Contacts: API reference.
• WhatsApp webhooks and phone number webhooks: template reviews, number lifecycle.
• Phone numbers: buying, porting, KYC and per-country pricing.