NextCloud is an open source collaboration platform. It is an alternative to Google Drive. OnlyOffice integration also makes it an alternative to Google Docs.
Open NextCloudSiyuan is an open source notes, and organization app. It is an alternative to Notion.
Open SiyuanFile managing interface used to upload, delete, preview and edit files
Open File BrowserWiki.js is an open-source wiki platform designed for team collaboration and documentation
Open WikiJS