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.
Hugo is an open-source static site generator written in Go.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Twitter is a 'microblogging' system that allows you to send and receive short posts called tweets.
Varnish is a reverse caching proxy.