DDoS-Guard is a Russian Internet infrastructure company which provides DDoS protection, content delivery network services, and web hosting services.
Google Analytics is a free web analytics service that tracks and reports website traffic.
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.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Ruby on Rails is a server-side web application framework written in Ruby under the MIT License.
VK is a Russian online social media and social networking service.