Hubzilla provides a platform for powerful extensions called plugins (or addons). These are independent modules that can be downloaded and activated by the hub admin to provide additional capabilities or custom features. Hubzilla provides a a wealth of hooks through the core functions, allowing plugins to extend functionality in rich and versatile ways.
Collections of plugins are added as repositories: typically git repos for convenient downloading and updating. All officially supported plugins are in the hubzilla-addons repo.
Unofficial plugins are listed here as a showcase for what plugins can do, but they are not supported by the Hubzilla project and are not guaranteed to be safe, so install at your own discretion. If a plugin repo is reported to be problematic, it will of course be removed from this list.