Apple Sign-in is based on OAuth 2.0 and OpenID Connect, and provides a privacy-friendly way for users to sign in to websites and apps.
cdnjs is a free distributed JS library delivery service.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
Paidy is basically a two-sided payments service, acting as a middleman between consumers and merchants in Japan.