HTTP Strict Transport Security (HSTS) informs browsers that the site should only be accessed using HTTPS.
JSDelivr is a free public CDN for open-source projects. It can serve web files directly from the npm registry and GitHub repositories without any configuration.
Mailchimp is a marketing automation platform and email marketing service.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Pingdom RUM(Real User Monitoring) is a feature of the Pingdom website monitoring and performance testing service. RUM enables you to collect and analyse data on how real users are experiencing your website.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.
YouTube is a video sharing service where users can create their own profile, upload videos, watch, like and comment on other videos.