Apache is a free and open-source cross-platform web server software.
Calendly is an app for scheduling appointments, meetings, and events.
Google Analytics is a free web analytics service that tracks and reports website traffic.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Typekit is an online service which offers a subscription library of fonts.