cdnjs is a free distributed JS library delivery service.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Moment.js is a free and open-source JavaScript library that removes the need to use the native JavaScript Date object directly.
OpenResty is a web platform based on nginx which can run Lua scripts using its LuaJIT engine.
PHP is a general-purpose scripting language used for web development.
Unpkg is a content delivery network for everything on npm.