This Express middleware for Twilio webhooks makes it easy to secure your Node.js app against non-Twilio requests by validating the request signature included in the HTTP headers sent by Twilio. The middleware can be easily integrated into an existing Express application, and it also provides API sugar to make rendering TwiML responses more concise. To use this middleware, you need to configure a system environment variable with your Twilio auth token and then pass the `twilio.webhook()` function to the Express route handler for the webhook endpoint. The middleware will automatically validate the request signature and return an HTTP response with a 403 status code if the signature is invalid.