Cloudflare Browser Insights is a tool that measures the performance of websites from the perspective of users.
Gravatar is a service for providing globally unique avatars.
Leaflet is the open-source JavaScript library for mobile-friendly interactive maps.
Lightbox is small javascript library used to overlay images on top of the current page.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache.
PHP is a general-purpose scripting language used for web development.