Ben Doherty (Oomph, Inc)

Resize images on the fly! Great for theme developers who add image sizes to their theme after image assets have already been added to the image library – images come out the right size, every time.
Works great for both single-site and multi-site installations. Multi-site installation requires SUNRISE to be set and wp-content/sunrise.php to be populated – Instructions are given within the plugin.

Oomph WP Inline Image Resize

Resize images on the fly! Great for rapid theme development when your image sizes may change often!

Yoast

Enrico Battocchi

This plugin allows users to clone posts of any type, or copy them to new drafts for further editing.
How it works:
<ol>
<li>
In ‘Edit Posts’/’Edit Pages’, you can click on ‘Clone’ link below the post/page title: this will immediately create a copy and return to the list.
</li>
<li>
In ‘Edit Posts’/’Edit Pages’, you can select one or more items, then choose ‘Clone’ in the ‘Bulk Actions’ dropdown to copy them all at once.
</li>
<li>
In ‘Edit Posts’/’Edit Pages’, you can click on ‘New Draft’ link below the post/page title.
</li>
<li>
On the post edit screen, you can click on ‘Copy to a new draft’ above “Cancel”/”Move to trash” or in the admin bar.
</li>
<li>
While viewing a post as a logged in user, you can click on ‘Copy to a new draft’ in the admin bar.
</li>
</ol>
3, 4 and 5 will lead to the edit page for the new draft: change what you want, click on ‘Publish’ and you’re done.
There is also a template tag, so you can put it in your templates and clone your posts/pages from the front-end. Clicking on the link will lead you to the edit page for the new draft, just like the admin bar link.
Duplicate Post has many useful settings to customize its behavior and restrict its use to certain roles or post types. Check out the extensive documentation on <a href="https://yoast.com/wordpress/plugins/duplicate-post/" rel="nofollow ugc">yoast.com</a> and our <a href="https://developer.yoast.com/duplicate-post/overview/" rel="nofollow ugc">developer docs</a>.
<h3>Contribute</h3>
If you find this useful and if you want to contribute, there are two ways:
<ol>
<li>Submit your bug reports, suggestions and requests for features on <a href="https://github.com/Yoast/duplicate-post" rel="nofollow ugc">GitHub</a>;</li>
<li>If you want to translate it to your language (there are just a few lines of text), you can use the <a href="https://translate.wordpress.org/projects/wp-plugins/duplicate-post" rel="nofollow ugc">translation project</a>;</li>
</ol>

Yoast Duplicate Post

This plugin is a very useful addition to the limited standard WordPress options. I often use the clone feature to create new posts/pages from existing ones. The options page allows setting the standard name for the copy as well as the attributes that should be transferred. 

Very useful addition


My plugin offers portfolio pages in addition to posts and pages. This plugin does not offer duplication option from portfolio pages. Although it appears to work for posts and pages.


Does not work for portfolio pages


I use this usefull plugin in every Wordpress website I design


Best duplicate posttypes plugin

The go-to tool for cloning posts and pages, including the powerful Rewrite & Republish feature.

Oomph WP Inline Image Resize vs Yoast Duplicate Post