ownCloud

Best known as an open-source alternative to Dropbox, ownCloud is an online file storage and personal cloud solution that allows users to store, share, and sync documents, music, pictures, contacts, calendars and bookmarks across multiple platforms. Linux-based ownCloud server is written in PHP and JavaScript, while native ownCloud client is available for desktops (Linux, BSD, OS X and Windows) and mobile phones (Android, iOS), as well as accessible via web browser. The ownCloud server supports external storage (via NAS, Samba, Dropbox, S3, Google Drive), remote access and mount via WebDAV, multiple database backends (MySQL, MariaDB, SQLite, Oracle DB), collaborative document editing via online editor, file versioning, music streaming, server-side encryption, and HTTPS/SSL. ownCloud can be extended via third-party ownCloud apps.