natthasath

Site Grayscale Toggle lets you turn your entire site grayscale and give visitors a clear on/off switch. It’s built to be CSP-friendly (no inline JS) and to avoid a flash-of-unstyled-content by injecting the initial state on the server side.
Features: 
– Grayscale filter site-wide via <code>html.is-grayscale { filter: grayscale(var(--sgt-level)); }</code>. 
– Intensity control (0–100) from Settings → Site Grayscale. 
– Show/Hide floating toggle button (bottom-right by default). 
– Shortcode: <code>[grayscale_toggle]</code> to place the switch anywhere (headers, menus, footers, blocks, widgets). 
– Remembers visitor preference with <code>localStorage</code> across pages. 
– CSP-safe: no inline JS; initial state added server-side to <code><html></code> to avoid FOUC. 
– Lightweight, theme-agnostic; works alongside most caching/CDN plugins.
Use cases include memorial/monochrome modes, accessibility preferences, or design experiments that you want users to control.

Site Grayscale Toggle

CSP-safe plugin that applies a site-wide grayscale filter with a front-end toggle. Control intensity (0–100) and whether to show a floating toggle but …

jojoee

Automatically turn the site to grayscale (may be used for some purpose)
Features:
<ul>
<li>Grayscale / Color switcher (for non-IE)</li>
<li>Theme option to enable / disable switcher and select switcher position</li>
<li>Default mode, ability to set default which either “grayscale” or “color”</li>
<li>Ignored Post IDs, user can display this plugin for specific posts by post IDs</li>
<li>Custom css</li>
</ul>
Compatible with all browsers:
<ul>
<li><a href="https://www.google.com/chrome/" rel="nofollow ugc">Google Chrome</a> 19+</li>
<li><a href="https://www.mozilla.org/firefox/" rel="nofollow ugc">Mozilla Firefox</a> 3.5+</li>
<li><a href="http://www.apple.com/safari/" rel="nofollow ugc">Safari</a> 6+</li>
<li><a href="https://www.microsoft.com/en-us/download/internet-explorer.aspx" rel="nofollow ugc">Internet Explorer</a> 8-9</li>
<li><a href="http://www.opera.com/" rel="nofollow ugc">Opera</a> 11.5</li>
</ul>
<h3>Notes</h3>
<ul>
<li><a href="https://codex.wordpress.org/WordPress_Coding_Standards" rel="nofollow ugc">WordPress Coding Standards</a></li>
<li>2 spaces for indent</li>
<li><a href="https://github.com/jojoee/grayscale-body" rel="nofollow ugc">Repository on Github</a></li>
</ul>
<h4>TODO</h4>
<ul>
<li>[x] Switcher</li>
<li>[x] Theme option</li>
<li>[ ] Localization</li>
<li>[ ] Separate utility out of main plugin file</li>
<li>[ ] Using the feature from <a href="https://github.com/jojoee/grayscale-body-js" rel="nofollow ugc">grayscale-body-js</a> instead</li>
</ul>
<h4>Thank you</h4>
<ul>
<li><a href="https://wordpress.org/plugins/about/validator/" rel="ugc">WordPress Plugin readme.txt Validator</a></li>
<li><a href="https://autoprefixer.github.io/" rel="nofollow ugc">Autoprefixer CSS online</a></li>
<li><a href="https://tinypng.com/" rel="nofollow ugc">TinyPNG</a></li>
<li><a href="https://www.piliapp.com/php-syntax-check/" rel="nofollow ugc">PHP code syntax check</a></li>
</ul>

Grayscale Body

Nice

Automatically turn the site to grayscale (may be used for some purpose)

Site Grayscale Toggle vs Grayscale Body