Websites that have a shopping cart or checkout page, either using a known ecommerce platform or a custom solution.
Express is a web application framework for Node.js, released as free and open-source software under the MIT License. It is designed for building web applications and APIs.
Google Tag Manager is a tag management system (TMS) that allows you to quickly and easily update measurement codes and related code fragments collectively known as tags on your website or mobile app.
Varnish is a reverse caching proxy.