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WapNotify receives WhatsApp events (incoming messages, delivery status updates) via a webhook endpoint registered with Meta. This page explains the webhook mechanism for developers integrating or debugging.

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Webhook endpoints

MethodPathPurpose
GET/api/webhookMeta webhook verification (hub challenge)
POST/api/webhookInbound messages and status updates
Both endpoints are public — no Authorization header is needed. Security is provided by HMAC signature verification on POST requests.

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Webhook verification (GET)

When you register your webhook URL in Meta, Meta sends a GET request to verify ownership: 
GET /api/webhook?hub.mode=subscribe&hub.verify_token=YOUR_VERIFY_TOKEN&hub.challenge=CHALLENGE_STRING
WapNotify checks that hub.verify_token matches the Webhook Verify Token stored in your workspace settings. If it matches, it responds with the hub.challenge value and a 200 status. If verification fails, check that the Verify Token in Meta matches exactly what you entered in Settings → WhatsApp Setup.

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Inbound events (POST)

Meta sends a POST request for every event — incoming messages, delivery receipts, read receipts.

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Signature verification

Every POST request includes an x-hub-signature-256 header: 
x-hub-signature-256: sha256=<hmac_hex>
WapNotify computes HMAC-SHA256(raw_body, app_secret) and compares it to the header value. Requests that fail signature verification are rejected with 403 Forbidden. The app_secret is the App Secret stored in your workspace WhatsApp settings (from Meta → Settings → Basic).

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Example: inbound text message

{
  "object": "whatsapp_business_account",
  "entry": [
    {
      "id": "WABA_ID",
      "changes": [
        {
          "value": {
            "messaging_product": "whatsapp",
            "metadata": {
              "display_phone_number": "919876543210",
              "phone_number_id": "PHONE_NUMBER_ID"
            },
            "contacts": [
              {
                "profile": { "name": "Rahul Sharma" },
                "wa_id": "919876543210"
              }
            ],
            "messages": [
              {
                "from": "919876543210",
                "id": "wamid.HBgLOTE5ODc2...",
                "timestamp": "1719859200",
                "text": { "body": "Hello, I'd like to place an order." },
                "type": "text"
              }
            ]
          },
          "field": "messages"
        }
      ]
    }
  ]
}

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Example: delivery status update

{
  "object": "whatsapp_business_account",
  "entry": [
    {
      "id": "WABA_ID",
      "changes": [
        {
          "value": {
            "messaging_product": "whatsapp",
            "statuses": [
              {
                "id": "wamid.HBgLOTE5ODc2...",
                "status": "delivered",
                "timestamp": "1719859260",
                "recipient_id": "919876543210"
              }
            ]
          },
          "field": "messages"
        }
      ]
    }
  ]
}
Status values: sent, delivered, read, failed.

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Retry behaviour

Meta retries failed webhook deliveries (non-2xx responses) with exponential backoff. WapNotify deduplicates messages using the wa_message_id field — receiving the same message ID twice is safe.