DDoS-Guard is a Russian Internet infrastructure company which provides DDoS protection, content delivery network services, and web hosting services.
Facebook pixel is an analytics tool that allows you to measure the effectiveness of your advertising.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Priority Hints exposes a mechanism for developers to signal a relative priority for browsers to consider when fetching resources.
Tilda is a web design tool.