Calendly is an app for scheduling appointments, meetings, and events.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Tilda is a web design tool.
Variti is a network security solutions firm that blocks bad bots, protects users from various automated abuse, attacks and fraud techniques.