Text messages

The simplest send, and the one with the most rules attached — because free-form text is exactly what Meta's service window governs.

On Cloud API

cURL

curl -X POST https://api.wpai.co.in/api/messages/send \
  -H "X-API-Key: $WPAI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "919876543210",
    "channel": "whatsapp_cloud",
    "type": "text",
    "text": "Your table is confirmed for 8pm. See you soon!"
  }'

Maximum 4096 characters.
Link previews are off. There is no parameter to turn them on through this endpoint.
Costs nothing from the wallet — the conversation the customer opened is already paid for.

On WhatsApp Web

cURL

curl -X POST https://api.wpai.co.in/api/messages/send \
  -H "X-API-Key: $WPAI_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "to": "919876543210",
    "channel": "whatsapp_web",
    "channelConnectionId": "68b2…",
    "type": "text",
    "text": "Your table is confirmed for 8pm. See you soon!"
  }'

Up to 65,536 characters, and no service window at all — you can message anyone at any time.
Returns status: "queued". The pacing queue decides when it actually goes.
Omit channelConnectionId and the oldest paired session sends it. With more than one number connected, name it.

Spintax is not resolved here

Bulk sends vary their wording per recipient. A single send through this endpoint does not: {{a|b}} is transmitted literally.

When it is refused

Cloud API: the window is closed

400

{
  "error": "The 24-hour service window is closed — you can only send approved templates to this number."
}

The window opens when the customer messages you and stays open 24 hours. A contact who has never written in has a closed window from the start — so this is the expected response for a first contact, not a misconfiguration.

Send an approved template instead. That is what templates are for, and it is the only way to reach a cold number on this channel.

WhatsApp Web: the number is held

409

{
  "error": "Sending is paused on this WhatsApp number because its deliveries were failing. Resume it on the Channels page."
}

Also possible: 404 No connected WhatsApp Web session for this organization when nothing is paired, and 503 WhatsApp Web service is unavailable, which is always transient and safe to retry.

Send overview Media messages