Dave Ligthart

A simple way to choose a default thumbnail for your post.
Works alongside the featured image core functionality.
For theme usage:
<h4>Add this function where you want the thumbnail to appear</h4>
<pre><code><?php if(function_exists('wct_thumb')){ wct_thumb(); } ?>
</code></pre>

WP-Choose-Thumb

A simple way to add a default thumbnail to your post.

aviplugins.com

When images are uploaded in the WordPress Media library section WordPress creates some thumbnails of that image. The size of these thumbnail images can be mentioned in the <code>Settings->Media</code> section.
But there can be some big issues with these thumbnails. WordPress Crop/Resize these images dynamically when you upload an image. When thumbnails are CROPPED it is very much possible that it gets CROPPED from the wrong section of the uploaded image. This can produce some BAD looking thumbnail images. Which doesn’t look good in frontend of the site. This plugin will allow you to update those thumbnail images manually. The thumbnail image edit interface that this plugin provides is simple and very easy to use.
The shortcodes and functions are provided in the image editor page of the plugin.
Image editor links can be found in WordPress Media Library.
Image files that can be edited are JPG, JPEG, GIF and PNG
<h4>Thumbnail Editor PRO</h4>
<a href="https://www.aviplugins.com/thumbnail-editor-pro/" rel="nofollow ugc">Checkout the PRO version features here</a>. PRO version costs only USD 2.00
<ul>
<li>Support for Amazon S3 Bucket.</li>
<li>Completely replace thumbnail images and upload new ones.</li>
<li>Add Custom Texts to thumbnail images. You can add signature in the images.</li>
<li>Different Text Fonts are available to choose from.</li>
<li>Add Image Effects like Gray Scale, Sketch, Negative or Add Color Effects to the Image.</li>
<li>Add image Borders with different border colors.</li>
<li>Option to Revert Back the changes you made in the image.</li>
</ul>

Thumbnail Editor

This is a very easy to use plugin that can be used to replace default WordPress image thumbnails.
This will make your images look good when you use them in your site. You can use shortcode to display images in your post or page.



Easy to use

Manually Crop and Resize thumbnail images that are uploaded in the Media section.

WP-Choose-Thumb vs Thumbnail Editor