wework4web

With the help of the shortcode, this plugin helps you to resize your image in different size. You never need to update your thumbnail size settings and re-upload all the image as you used to do before. It gives you the unlimited limitation for image resize.
How To Use
[image-resize width=100 height=100 ref=w default=your_default_image.png]
Parameters: 
width: (required) Width of the image in px
height: (required) Height of the image in px
Ref: (optional) w if you want the width reference, h for height reference. No ref parameter means you will have image with maintained ratio.
default: (optional) Your default image path. The default image is shown when you don’t have featured image in your post.
You can use the shortcode in your post,page content area.
For using in templates, you can use the wordpress do_shortcode function. Like:
<?php do_shortcode(‘[image-resize width=100 height=100 ref=w default=your_default_image.png]’); ?>
While using in templates, it must be inside the post loop.
If you have any queries do write in the support section.

Image Resizer On The Fly

This plugin resize featured image on the fly and gives u ability to remove automatically resized image from admin.

FutrX

“OptimizeGenie” is a WordPress plugin that helps you optimize your website to get the best performance and speed. This plugin is very easy to use and has a very simple user interface.
With “Optimize Genie” you can optimize your website in a few clicks.
This plugin will help you:
<ul>
<li>Manipulate and Customize the sizes on your images.</li>
<li>Add ?width={number} to the end of your image URL to resize it on the fly. This includes all images under wp-content/, which inlcudes themes, plugins or media library images.</li>
</ul>

OptimizeGenie

"OptimizeGenie" is a WordPress plugin that helps you optimize your website to get the best performance and speed.

Image Resizer On The Fly vs OptimizeGenie