ownCloud

ownCloud is a free and open-source software platform that enables individuals and organizations to host their own file synchronization and sharing service. It provides a web interface, desktop and mobile clients, and APIs to access, synchronize, and share files across devices, while giving administrators control over data location and access. The project emphasizes data sovereignty, privacy, and interoperability with standard protocols such as WebDAV, CalDAV, and CardDAV, and supports features like external storage, file versioning, activity feeds, sharing controls, and optional encryption.

The project was launched in 2010 by Frank Karlitschek as an open-source solution for self-hosted cloud storage. It has been developed by the ownCloud community and the ownCloud GmbH. In 2016 a separate fork called Nextcloud was created by core developers who departed from the original project; since then Nextcloud has continued as a distinct ecosystem, while ownCloud remains active with its own governance and enterprise offerings.

Core components include the ownCloud Server, primarily written in PHP, with a relational database backend (MySQL/MariaDB or PostgreSQL) and a modular app framework accessed through a web-based administration console. The architecture supports a growing set of add-on apps for document collaboration, tagging, calendars, contacts, and other integrations. The community edition is released under the AGPLv3 license, while an enterprise edition provides commercial support and additional features.

Deployment is self-hosted on Linux servers, typically using Apache or Nginx, PHP, and a database. It can be run on premises, in private clouds, or in virtualized environments, and is complemented by a broad ecosystem of clients, third-party storage integrations, and federation capabilities.