WordPress.org

Ella

This plugin allows you to create documents with WordPress, and to share them with others so they can also read and edit. Share the unique link to let anyone edit, or restrict access to specific email addresses.
With the Gutenberg plugin, Docs supports real-time collaborative editing — multiple users can edit the same document simultaneously, seeing each other’s cursors and changes live.
<h3>Sharing</h3>
The share panel (in the document sidebar) lets you control access:
<ul>
<li>Anyone with the link — anonymous users get a randomly generated animal name and emoji avatar (e.g. “Anonymous Fox”). They can edit text but cannot upload files.</li>
<li>Specific people — invite collaborators by email. They receive a magic link to access the editor. Email-invited users can upload files.</li>
<li>Existing users — add collaborators from the user autocomplete. They get full editing and upload access.</li>
<li>Restricted — only the document author and invited people can access.</li>
</ul>
<h3>How it works</h3>
Documents live entirely in wp-admin — there’s no public frontend. Each doc gets a unique and secret shareable URL that opens the editor directly.
Anonymous visitors don’t create any database entries. Their identity exists only in a browser cookie and disappears when it expires.
Email-invited people are created as real WordPress users (without a role) so their edits show up in revision history. They log in via magic links sent to their email.

Docs

how it works? 
Can I use it in the classic editor?

how it works

Create and share documents with WordPress!

sund

Have you ever been frustrated with manually copying and pasting article/post content between WordPress and Google Docs for collaboration? Wave by Codox will turn WordPress into a real-time CMS, so your team can collaboratively edit blogs/posts/articles in real-time.
Major features in Codox Wave include:
<ul>
<li>See each other’s edits instantly when your team works at the same time on the same post or page inside WordPress.</li>
<li>Edit with TinyMCE. Posts are ready to go when you finish. </li>
<li>Work together securely and with confidence. We don’t store any posts or content on our server.</li>
</ul>

Wave

Wave by Codox enables teams to real-time co-edit and co-iterate posts directly in your WordPress site.

Docs vs Wave