AddThis is a social bookmarking service that can be integrated into a website with the use of a web widget.
Apache is a free and open-source cross-platform web server software.
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.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.