How to post to a channel in Node.js with the Wapito WhatsApp API

// Post to Channel with the Wapito WhatsApp API.
//
// Send to the channel id like any recipient, upload media once and reuse it, prefer link posts for traffic, and confirm from the status event.
//
// Run it with:
//   export WAPITO_TOKEN="wpt_..."
//   node post-to-channel.mjs

const BASE_URL = 'https://api.wapito.com/v1';
const TOKEN = process.env.WAPITO_TOKEN;

// --- Publish a text post ---
{
  const url = BASE_URL + '/messages/text';
  const options = {
    method: 'POST',
    headers: {Authorization: 'Bearer ' + TOKEN, 'Content-Type': 'application/json'},
    body: '{"to":"+15551234567","body":"Your order #4182 has shipped. Track it here: https://acme.example/t/4182","typing_time":3}'
  };

  try {
    const response = await fetch(url, options);
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error(error);
  }
}

// --- Post an image with a caption ---
{
  const url = BASE_URL + '/messages/image';
  const options = {
    method: 'POST',
    headers: {Authorization: 'Bearer ' + TOKEN, 'Content-Type': 'application/json'},
    body: '{"to":"+15551234567","media":"https://acme.example/labels/4182.png","caption":"Your shipping label for order #4182"}'
  };

  try {
    const response = await fetch(url, options);
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error(error);
  }
}

// --- Share a link with a preview ---
{
  const url = BASE_URL + '/messages/link';
  const options = {
    method: 'POST',
    headers: {Authorization: 'Bearer ' + TOKEN, 'Content-Type': 'application/json'},
    body: '{"to":"+15551234567","url":"https://acme.example/t/4182","title":"Track order #4182","description":"Out for delivery, arriving before 18:00.","image":"https://acme.example/og/tracking.png","body":"Your parcel is on the van:"}'
  };

  try {
    const response = await fetch(url, options);
    const data = await response.json();
    console.log(data);
  } catch (error) {
    console.error(error);
  }
}

import crypto from 'node:crypto';
import express from 'express';

const app = express();
const SECRET = process.env.WAPITO_WEBHOOK_SECRET;
const EVENTS = new Set(['messages', 'messages.status']);

/** Checks the X-Wapito-Signature header: t=<ms>,v1=<hex hmac-sha256>. */
function verify(raw, header) {
  if (!header) return false;
  const parts = Object.fromEntries(header.split(',').map((p) => p.split('=')));
  if (!parts.t || !parts.v1) return false;
  if (Math.abs(Date.now() - Number(parts.t)) > 300_000) return false; // 5 minute clock skew
  const expected = crypto.createHmac('sha256', SECRET).update(`${parts.t}.`).update(raw).digest('hex');
  const a = Buffer.from(expected, 'hex');
  const b = Buffer.from(parts.v1, 'hex');
  return a.length === b.length && crypto.timingSafeEqual(a, b);
}

app.post('/wapito', express.raw({ type: 'application/json' }), (req, res) => {
  if (!verify(req.body, req.get('X-Wapito-Signature'))) return res.sendStatus(401);
  const payload = JSON.parse(req.body.toString('utf8'));
  if (EVENTS.has(payload.event)) console.log(payload.event, payload.data);
  res.sendStatus(200); // answer 2xx fast; do the real work in a queue
});

app.listen(Number(process.env.PORT ?? 3000));