Apache is a free and open-source cross-platform web server software.
Leaflet is the open-source JavaScript library for mobile-friendly interactive maps.
Mailchimp is a marketing automation platform and email marketing service.
Mapbox GL JS is a JavaScript library that uses WebGL to render interactive maps from vector tiles and Mapbox styles.
Unpkg is a content delivery network for everything on npm.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.