Docs

End-to-end encryped email and docs.

skiff.com

Collaboration for documents, wireframes, flow charts and more.

whimsical.com

End-to-end encryped, open-source document collaboration suite, including spreadsheets.

cryptpad.fr

A wide range of tools for businesses with a commitment to privacy (note that data is shared with third-parties).

zoho.com

Real-time collaboration in Markdown.

hackmd.io

Docs, tables, databases, collaboration – Notion has become an incredibly popular tool for teams of all sizes.

notion.so