Nuclino is a collaborative document editing service from Germany.
European document collaboration services
A document collaboration service allows users to work together on documents, spreadsheets, presentations, or the like.
This category contains services from companies based in a member state of the European Union (EU), the European Economic Area (EEA) and the European Free Trade Association (EFTA).
You can read more about the listing criteria here.
European services
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.
XWiki is an open-source platform for knowledge management and collaboration, built in Europe, with a focus on digital sovereignty. It helps teams create, structure, and share information efficiently across departments, projects, or entire organizations. XWiki can be deployed self-hosted or cloud-based, giving full control over data location and compliance needs. XWiki features a browser-based WYSIWYG editor, nested pages, version history, and granular permissions. It enables collaborative editing, content reuse through templates, and advanced navigation across linked documentation. The platform supports multilingual content and includes tools to structure data through forms and custom metadata.
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.