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.
Other products in category Document collaboration services
Infomaniak kDrive is the file hosting and collaborative document editing service of the Swiss cloud provider Infomaniak. The document editing service if based on the open source tool OnlyOffice.
Proton Docs let you collaborate in real time, leave comments, add photos, and store your documents securely. Proton Docs and also the spreadsheet product Proton Sheets, is part of the bigger Proton Drive product.