BuddyPress

BuddyPress is a GPL-licensed open-source community plugin for WordPress that adds social-network functionality to a WordPress site. It provides user profiles, groups, activity streams, notifications, and related features, and can be used partially by enabling only selected components; the interface adapts to show only the menu items, pages, and buttons for enabled features.

Its components include Profiles with custom fields and visibility levels, Settings for account and email preferences, Groups for user-created micro-communities, Activity Streams for members and groups, Notifications with read/unread tracking, Friendships, and Private Messaging. It integrates with bbPress for community forums and can be extended with third-party components. It also exposes a REST API, and releases include security and maintenance updates.

BuddyPress is aimed at site owners building campus or school social networks, internal company communication tools, niche interest communities, and product or service communities. It is distributed as open-source software under the GPL license; no paid editions, trials, or seat-based plans are described.