nextcloud/server

Nextcloud is a self-hosted cloud storage and collaboration platform that lets individuals and organizations store their files, contacts, calendars, and other personal data on their own server rather than on a commercial cloud service like Google Drive or Dropbox. The core problem it solves is data sovereignty: you control where your data lives, who can access it, and what happens to it, rather than delegating that control to a third party. The server software handles file storage and synchronization across devices, sharing files with other people (including users on other Nextcloud instances through a feature called federation), and a permission system that controls what others can see or edit. Beyond basic file storage, Nextcloud extends through a large app ecosystem. Optional apps add functionality like a calendar, contacts manager, email client, and video calling. These apps integrate with the core file system and authentication so everything works under one login. The technical stack is PHP for the server backend with a JavaScript frontend, and it requires a web server like Apache or Nginx and a database like MySQL or PostgreSQL to run. Installation can be done on personal hardware, a rented virtual private server, or through appliances and managed hosting providers that ship Nextcloud pre-installed. You would use Nextcloud if you are a privacy-conscious individual who wants Dropbox-like syncing without the subscription or the data sharing concerns, or if you are a business or organization that needs to share documents internally while keeping data within your own infrastructure for compliance or security reasons. It is licensed under the AGPL open-source license, meaning you can run and modify it freely, though a commercial enterprise version with support contracts is also available.