Marcelo Pedra

AMPM Dashboard Admin Note adds an “Important Note” widget to the WordPress Dashboard (wp-admin → Dashboard). Only administrators (capability <code>manage_options</code>) and (in Multisite) Super Admins can view and edit it.
Features:
<ul>
<li>Visual editor (TinyMCE) inside the dashboard widget.</li>
<li>AJAX saving with feedback (“Saving…” label + spinner).</li>
<li>Strict sanitization via allowlist (wp_kses) and limited inline styles (color, background-color, text-align).</li>
<li>Links forced to <code>target="_blank"</code> with <code>rel="nofollow noopener noreferrer"</code>.</li>
<li>Widget severity/color: Neutral / Info / Warning / Error.</li>
<li>Shows: “Modified by: user_login (Display Name. ID: X) — date/time” using the site timezone configured in WordPress.</li>
<li>Multisite-friendly: stored per site (blog) by default.</li>
</ul>
<h3>Translations</h3>
<ul>
<li>English (Default)</li>
<li>Spanish (Español)</li>
<li>Argentinean Spanish (Español de Argentina)</li>
<li>Dutch (Nederlands)</li>
<li>French (Français)</li>
<li>German (Deutsch)</li>
<li>Italian (Italiano)</li>
<li>Portuguese (Português brasileiro)</li>
</ul>

AMPM Dashboard Admin Note

Displays a single admin-only Dashboard widget (“Important Note”) with TinyMCE editing and AJAX save.

Iftekhar Bhuiyan

AdminPad allows WP site admin (only) to write down simple note from WP dashboard using simple widget. Deleting this plugin will also delete data saved by this plugin on your database.
Features: 
* Light weight plugin. 
* Simple user interface.

AdminPad

AdminPad is a simple note taker for site administrator only.

AMPM Dashboard Admin Note vs AdminPad