Mensagens de WhatsApp pelo seu sistema, sem dor de cabeça.

API=https://api.w2-api.com

curl -X POST "$API/instances/$ID/messages/text" \
  -H "Authorization: Bearer $TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"to":"5511999999999","text":"Pedido #4821 enviado"}'

const API = "https://api.w2-api.com";

const res = await fetch(
  `${API}/instances/${ID}/messages/text`,
  {
    method: "POST",
    headers: {
      Authorization: `Bearer ${TOKEN}`,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({
      to: "5511999999999",
      text: "Pedido #4821 enviado",
    }),
  }
);
console.log(res.status); // 202

import requests

API = "https://api.w2-api.com"

r = requests.post(
    f"{API}/instances/{ID}/messages/text",
    headers={"Authorization": f"Bearer {TOKEN}"},
    json={"to": "5511999999999", "text": "Pedido #4821 enviado"},
)
print(r.status_code)  # 202

$api = "https://api.w2-api.com";

$ch = curl_init("$api/instances/$id/messages/text");
curl_setopt_array($ch, [
  CURLOPT_POST => true,
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer $token",
    "Content-Type: application/json",
  ],
  CURLOPT_POSTFIELDS => json_encode([
    "to" => "5511999999999",
    "text" => "Pedido #4821 enviado",
  ]),
]);
curl_exec($ch);
echo curl_getinfo($ch, CURLINFO_HTTP_CODE); // 202

Troque ID e TOKEN pelos valores do seu painel.