Google Analytics is a free web analytics service that tracks and reports website traffic.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
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.
reCAPTCHA is a free service from Google that helps protect websites from spam and abuse.
Stripe offers online payment processing for internet businesses as well as fraud prevention, invoicing and subscription management.
Unpkg is a content delivery network for everything on npm.