WebMaestro.Fr

Upload the layers of your image, and create a parallax effect !
It works great on smart devices too !
The first step is to create with your favorite picture editing software (Photoshop, GIMP…) an independent image for each ground composing your image. All these layers shall be the same size, and should be in .png format as they are meant to include transparency areas. 
Then, on your post editing page in WordPress, click the Insert Media button, and (the same way you would create a gallery) upload your layers under the Create Parallax item. Reorganise the layers if needed, from the background to the front. 
You can finally configure the animation (calibrate, invert, limit, scalar, friction), and publish !
There is <a href="http://webmaestro.fr/image-parallax-plugin-wordpress/" rel="nofollow ugc">some examples</a> on the plugin page.
It uses <a href="http://wagerfield.github.io/parallax/" rel="nofollow ugc">parallax.js</a> by Matthew Wagerfield.

Image Parallax

Create images with a parallax effect. Upload some layers, configure the animation, and publish !

Freemius

Abu Hayat

bPlugins

Charles Cormier

Md. Merajul Islam Sojib

The parallax effect is a modern web design technique where the background element scrolls slower than the foreground content. The parallax effect can be used on landing pages, long-form content, sales pages, or the homepage of a business website. It is a great way to highlight different sections on a lengthy page. 
You can easily create a parallax section with this plugin.
<h4>Features</h4>
<ul>
<li>Easy to use</li>
<li>It does not require much technical knowledge to use</li>
<li>It is lightweight because it relies on JavaScript</li>
</ul>
<a href="https://bblockswp.com/demo/parallax-section/" rel="nofollow ugc">Demos</a>
<h4>How to use</h4>
<ul>
<li>First, install the Parallax Section plugin</li>
<li>Add the Parallax Section block from the block category called “Widgets” in the Gutenberg editor.</li>
<li>You can change block settings from the right-side settings sidebar.</li>
<li>
Enjoy!
</li>
<li>
For installation help click on Installation Tab
</li>
</ul>
<h4>Feedback</h4>
<ul>
<li>Did you like this plugin? Dislike it? Do you have a feature request? <a href="mailto:support@bplugins.com" title="Send feedback" rel="nofollow ugc">Please share your feedback with us</a></li>
</ul>
<h3>Check out the Parent Plugin of this plugin-</h3>
<a href="https://bblockswp.com" rel="nofollow ugc">B Blocks</a> – A blocks collection and page building tool for Gutenberg.
<h3>Check out our other WordPress Plugins-</h3>
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<a href="https://bplugins.com/products/pdf-poster/" rel="nofollow ugc">PDF Poster</a> – Display/Embed PDF files with different styles.
<a href="https://bplugins.com/products/html5-audio-player/" rel="nofollow ugc">Html5 Audio Player</a> – Listen audios with awesome visuals.
<a href="https://bplugins.com/products/streamcast-radio-player/" rel="nofollow ugc">StreamCast</a> – Customizable radio player with different skins.
<a href="https://bplugins.com/products/3d-viewer/" rel="nofollow ugc">3D Viewer</a> – Embed 3D models and 3D products with interaction.
<a href="https://bplugins.com/products/advanced-post-block/" rel="nofollow ugc">Advanced Post Block</a> – Show posts and custom posts in different layouts.

Parallax Section Block – Add Parallax Scrolling Effects to Sections.

Add Parallax scrolling effects in any section of your website.

Image Parallax vs Parallax Section Block – Add Parallax Scrolling Effects to Sections.