Node.js SDK Examples

Configuration

const baseUrl = 'https://evoapi.faisak.com';
const apiKey = 'wg_live_replace_with_your_key';

Send Support Message

const response = await fetch(`${baseUrl}/api/send-message`, {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${apiKey}`,
    'Content-Type': 'application/json',
  },
  body: JSON.stringify({
    instance_id: 'demo-support-line',
    phone: '+9665XXXXXXX',
    message: 'Your support request has been updated.',
    message_purpose: 'support',
  }),
});

const json = await response.json();

Allowed purposes are transactional, operational, support, internal_team, and authentication. Do not use marketing, cold outreach, or bulk campaign purposes.

Handle Errors

if (!json.success) {
  const code = json.error || 'unknown_error';
  const message = json.message || 'Request failed.';

  // Common examples:
  // module_not_enabled, message_purpose_not_allowed,
  // recipient_suppressed, sending_throttled
  throw new Error(`${code}: ${message}`);
}

Verify Webhook Signature

import crypto from 'node:crypto';

function verifyWebhookSignature({ timestamp, rawBody, signature, secret }) {
  const expected =
    'sha256=' +
    crypto
      .createHmac('sha256', secret)
      .update(`${timestamp}.${rawBody}`)
      .digest('hex');

  return crypto.timingSafeEqual(Buffer.from(expected), Buffer.from(signature));
}

Express Webhook Receiver

import express from 'express';

const app = express();
const webhookSecret = 'replace_with_webhook_signing_secret';

app.post(
  '/webhooks/whatsapp-gateway',
  express.raw({ type: 'application/json' }),
  (req, res) => {
    const timestamp = req.header('X-WhatsApp-Gateway-Timestamp') || '';
    const signature = req.header('X-WhatsApp-Gateway-Signature') || '';
    const rawBody = req.body.toString('utf8');

    if (!verifyWebhookSignature({ timestamp, rawBody, signature, secret: webhookSecret })) {
      return res.status(401).send('Invalid signature');
    }

    const event = JSON.parse(rawBody);

    if (event.event === 'message.received') {
      // Handle event.from and event.message_text.
    }

    if (event.event === 'recipient.opted_out') {
      // Suppress event.from in your application.
    }

    return res.status(200).send('ok');
  }
);