Elgg
self-hosted, social networks and forums

Elgg is a powerful open-source social networking engine that enables individuals, organizations, and communities to create their own social networks and collaborative platforms. It provides a robust set of features including user profiles, activity streams, groups, and content sharing capabilities. Elgg is highly customizable and extensible, allowing developers to tailor it to their specific needs and integrate additional functionality through plugins. With its flexibility and scalability, Elgg is suitable for a wide range of social networking applications.