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.
PayPal is an online payments system that supports online money transfers and serves as an electronic alternative to traditional paper methods like checks and money orders.
Shopify is a subscription-based software that allows anyone to set up an online store and sell their products. Shopify store owners can also sell in physical locations using Shopify POS, a point-of-sale app and accompanying hardware.
Varnish is a reverse caching proxy.