cdnjs is a free distributed JS library delivery service.
Cloudflare is a web-infrastructure and website-security company, providing content-delivery-network services, DDoS mitigation, Internet security, and distributed domain-name-server services.
Swiper is a JavaScript library that creates modern touch sliders with hardware-accelerated transitions.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.