Apache is a free and open-source cross-platform web server software.
cdnjs is a free distributed JS library delivery service.
Google AdSense is a program run by Google through which website publishers serve advertisements that are targeted to the site content and audience.
HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
Leaflet is the open-source JavaScript library for mobile-friendly interactive maps.
PHP is a general-purpose scripting language used for web development.
Unpkg is a content delivery network for everything on npm.