Nextcloud is a free, open-source, self-hosted file sharing and collaboration platform. It allows users to store and share files, as well as collaborate on documents and other types of files. Nextcloud also includes features such as calendar and address book syncing, video and audio conferencing, and support for external storage. It can be installed on a variety of operating systems, including Windows, macOS, and Linux, and can be run on a wide range of hardware, including personal computers, servers, and virtual private servers. Nextcloud also provides a platform for creating and installing apps that add additional functionality to the platform. It is similar to other file sharing software like ownCloud, Google Drive and Dropbox.