One REST API for every channel you send on.

curl -X POST "$BROADCASTS_API_BASE/api/ext/v1/whatsapp/messages/text" \
  -H "X-API-Key: $BROADCASTS_API_KEY" \
  -H "Idempotency-Key: order-8842-confirmed" \
  -H "Content-Type: application/json" \
  -d '{
    "instanceId": "inst_9f2a",
    "to": "+919876543210",
    "text": "Your order #8842 has shipped! Track it here: https://trk.example/8842"
  }'

import fetch from "node-fetch";

const base = process.env.BROADCASTS_API_BASE;
const res = await fetch(base + "/api/ext/v1/whatsapp/messages/text", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.BROADCASTS_API_KEY,
    "Idempotency-Key": "order-8842-confirmed",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    instanceId: "inst_9f2a",
    to: "+919876543210",
    text: "Your order #8842 has shipped! Track it here: https://trk.example/8842",
  }),
});

const message = await res.json();
console.log(message.id, message.status);

import os, requests

response = requests.post(
    f"{os.environ['BROADCASTS_API_BASE']}/api/ext/v1/whatsapp/messages/text",
    headers={
        "X-API-Key": os.environ["BROADCASTS_API_KEY"],
        "Idempotency-Key": "order-8842-confirmed",
    },
    json={
        "instanceId": "inst_9f2a",
        "to": "+919876543210",
        "text": "Your order #8842 has shipped! Track it here: https://trk.example/8842",
    },
)

message = response.json()
print(message["id"], message["status"])