Toro_Unit (Hiroshi Urabe)

Simple Customization posts per page for your sites.
You can change posts per page by taxonomy or category or tag or custom post type.
<h4>Available Setting</h4>
<ul>
<li>Custom Post Type</li>
<li>Custom Taxonomy</li>
<li>Category</li>
<li>Tag</li>
</ul>
This plugin use <code>pre_get_posts</code>.
<a href="https://github.com/torounit/pppp" rel="nofollow ugc">This Plugin published on GitHub.</a>
Donation: Please send Amazon Gift to donate[at]torounit.com.
<h4>Translators</h4>
<ul>
<li>Japanese(ja) – <a href="https://www.torounit.com/" rel="nofollow ugc">Toro_Unit</a></li>
</ul>

Powerful Posts Per Page (PPPP)

Posts per page for custom post types and taxonomies.

Jabawack

Simple Custom Posts per Page (SCPP) allows to configure the number of posts displayed for every custom post registered in WordPress.
See <a href="https://wordpress.org/extend/plugins/simple-custom-posts-per-page/screenshots/" rel="ugc">Screenshots</a> to known why it is called “Simple”.
In your Readme page in Setting tab of WordPress, it adds an option for every post type.
Disable Plugin in Template: 
You can disable plugin filters in your template whenever you want. Maybe you need a query with a different number of custom posts per page for a specific post type. 
Using this code before your query, the filter plugin will be disabled for a specific post type:
<pre><code><?php $GLOBALS['ado_cspp_disable']="YOUR_TYPE"; ?>
</code></pre>
With this code, you can use your personalized query for your loop.
More: 
You can find more informations in the official <a href="http://www.adostudio.it/blog/simple-custom-posts-per-page-397/" rel="nofollow ugc">Post</a> on my Blog.

Simple Custom Posts per Page

This plugin allows to configure the number of posts displayed for every custom post registered.

Powerful Posts Per Page (PPPP) vs Simple Custom Posts per Page