Apache is a free and open-source cross-platform web server software.
Disqus is a worldwide blog comment hosting service for web sites and online communities that use a networked platform.
Elgg is a social networking engine, delivering the building blocks for creating social networks and applications.
Open Graph is a protocol that is used to integrate any web page into the social graph.
Progressive Web Apps (PWAs) are web apps built and enhanced with modern APIs to deliver enhanced capabilities, reliability, and installability while reaching anyone, anywhere, on any device, all with a single codebase.
ShareThis provides free engagement and growth tools (e.g., share buttons, follow buttons, and reaction buttons) for site owners.