Nextcloud offers open source server and client software to host your own cloud storage service like Dropbox or Google Drive. It is designed to be easy to use and secure. It can either be used as a self-hosted solution or via their hosted service.

The Product

Nextcloud offers clients to synchronize with Windows, MacOS, Linux and FreeBSD. It also offers mobile clients for Android and iOS. Their Features include file storage, sharing, and collaboration, as well as calendar, contacts, and email.