Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
Materialize CSS is a front-end framework that helps developers create responsive and mobile-first web applications. It is based on Google's Material Design guidelines.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
WhatsApp Business is a free to download app available on Android and iPhone using which businesses can connect with their customers.