Calendly is an app for scheduling appointments, meetings, and events.
GoatCounter is an open source web analytics platform available as a hosted service (free for non-commercial use) or self-hosted app. It aims to offer easy to use and meaningful privacy-friendly web analytics as an alternative to Google Analytics or Matomo.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Hugo is an open-source static site generator written in Go.
Open Graph is a protocol that is used to integrate any web page into the social graph.