QOwnNotes is a plain-text file notepad and todo-list manager with Markdown support and Nextcloud / ownCloud integration.
Dropbox is good for file syncing and sharing, but is not an ideal place for collaboration. So we build Seafile, a better place for managing documents together. In Seafile, you can create groups with file syncing, wiki, discussion and tasks. It enables you to easily collaborate around documents within a team. In addition, it is open source. So you can build a private cloud freely for your organization.