Phillip.Gooch

Backdrop is a site background customizer with power greater than the mere stock background selector included with WordPress. What can backdrop do that the default can’t? I’m glad you asked…
<ul>
<li>More than just boring backgrounds, flexible backgrounds, parallax backgrounds, even sliding backgrounds are stuffed in here too (don’t worry, the boring ones are still around as well).</li>
<li>Options, options, options! More options that you can shake a well sharpened stick at.</li>
<li>Uses the WordPress customizer interface so you can see your changes as you make them.</li>
<li>One click HiDpi (or retina) backgrounds, make it look all purdy on that fancy screen.</li>
<li>Theme schmeme, we don’t need support in your stinkin theme, backdrop can force it’s way into nearly any theme.</li>
<li>Calls external JS and CSS files that are appropriately cached.</li>
<li>Advanced options for those in the know with CSS.</li>
<li>Built for the smoothest animations possible.</li>
</ul>
Note: Starting with version 2.0 Backdrop will no longer work it’s magic with older versions of Internet Explorer (before version 10). If you want to support animations on older versions of IE then please use Backdrop 1.X.
Note: Your Backdrop settings will not be transfered from 1.X to 2.X, you will need to re-set your backdrop on update.

Backdrop

Backdrop is an improved site background customizer allowing for all manner of fancy things.

Ryan Novotny

Add the particles.js JavaScript library to add cool particle effects to any WordPress page ( demo: <a href="https://particlebackground.com/" rel="nofollow ugc">https://particlebackground.com/</a> ).
Uses shortcode or easy options for adding to the front page or blog page of WordPress.
Fully customize the particles using your own JSON or the built in color & density settings
Leave a comment in the support forum for any suggestions or bugs.
<h4>Features</h4>
Add particle background to home or blog pages with one click 
Add particle background to any page using shortcodes 
Customize the background color and dot color 
Add any HTML just like a WordPress post to display on top of the particle background (optional)

Particle Background WP

Particle Backgrounds WP lets you easily add cool particle-style backgrounds to any page.

Backdrop vs Particle Background WP