Nuclino is a collaborative document editing service from Germany.
European alternatives to Microsoft 365 Online
Microsoft 365 Online allows users to create, edit, and share documents through a web interface, without requiring local software installation. It is used globally by individuals, businesses, and educational institutions and can be integrated into existing IT environments. The service is one of the established platforms for browser-based document collaboration.
This pages lists European Microsoft 365 Online alternatives from companies based in a member state of the European Union (EU) or the European Free Trade Association (EFTA).
Nextcloud Office is the document collaboration service of the Nextcloud suite. Nextcloud is a open source file hosting service for self-hosting. Nextcloud Office is part of the Nextcloud suite and is based on the open source tool Collabora Online.
CryptPad is an open source document collaboration service that can be self-hosted. CryptPad is zero-knowledge, which means that the operator cannot read the content written on the site. Since it can be self-hosted there are many instances. The most known, which is also driven by the main developers however is cryptpad.fr.
Self-hosted & Open Source
Collabora Online is an open source document collaboration service. It can be self-hosted and is used by many cloud solutions like Nextcloud Office. They offer a text (Writer), spreadsheet (Calc), presentation (Impress) and vector graphics (Draw) editor.