cdnjs is a free distributed JS library delivery service.
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.
Lightbox is small javascript library used to overlay images on top of the current page.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Ubuntu is a free and open-source operating system on Linux for the enterprise server, desktop, cloud, and IoT.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.