cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
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.
Swiper is a JavaScript library that creates modern touch sliders with hardware-accelerated transitions.
VK is a Russian online social media and social networking service.