Kyle Charlton

<p>Save page and post notes in the editor or while logged in, add notes from the front end using the integrated notes button found in the admin bar.</p>
<h4>Features</h4>
<ul>
<li>Make page and post notes from both the front or back end (while logged in)</li>
<li>Front end: Lock the note box open or closed on a per page basis so you can select which pages or posts show your notes automatically</li>
<li>Front end: Movable note boxes</li>
<li>Front end: Notes are saved using Ajax which means no refresh when you click save</li>
<li>Front end: The positon of the note box saves automatically once you have finished moving it to your desired location (per page basis). </li>
<li>Front end: The note box is resizable, the dimentions are saved after each resize</li>
<li>Front end: Save status appears after every save action so you know when your notes, size and position are being saved  </li>
<li>Dashboard: Dashboard widget that will display all page/post notes with links to each page</li>
</ul>
<h4>Future Updates</h4>
<ul>
<li>Record user who made note (Pro version)</li>
<li>Create multiple notes/annotations on a single page for logged in users by role (Pro version)</li>
<li>Assign users to notes (users receive notification of new notes) (Pro version)</li>
<li>Make comments on notes (Pro version)</li>
</ul>


Site Notes

very useful

A plugin that adds a note box to  your posts and pages which can be viewed in the admin bar

Webliberty

<p>Use the Simple Note plugin to write informative and warning notes, notes about errors or success, as well as quotes in colored blocks.</p>
<h3>How to use</h3>
<p>Search beautiful colored blocks in Common blocks category and insert into the content.</p>
<h3>Translations</h3>
<p>You can translate Simple Note on <a href="https://translate.wordpress.org/projects/wp-plugins/simple-note" rel="nofollow ugc"><strong>translate.wordpress.org</strong></a>.</p>


Simple Note

The plugin allows you to create colored text notes in the new block editor.

Site Notes vs Simple Note