cdnjs is a free distributed JS library delivery service.
Fastly is a cloud computing services provider. Fastly's cloud platform provides a content delivery network, Internet security services, load balancing, and video & streaming services.
GitHub Pages is a static site hosting service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Spotify Widgets provide an embeddable view of a track, artist, album, user, playlist, podcast or episode for use within your web project.
Varnish is a reverse caching proxy.