Stephanie Leary

This is a utility for converting lots of posts or pages to a custom post type (or vice versa). You can limit the conversion to posts in a single category or children of specific page. You can also assign new taxonomy terms, which will be added to the posts’ existing terms.
This plugin is useful for converting many posts at once. If you’d rather do one at a time, use <a href="https://wordpress.org/extend/plugins/post-type-switcher/" rel="ugc">Post Type Switcher</a> instead.

Convert Post Types

Wordpress 4.9.5

No better plugin for converting categories to custom post types. And vice versa.

Still works great

A bulk conversion utility for post types.

Ron Zvagelsky

Monthly grid view calendar widget highlighting archived and/or future posts.
Additional Features:
<ul>
<li>Popup details for each date with posts</li>
<li>Optional details include post author and comment count.</li>
<li>Ability to show posts by post type, category, specific taxonomy and/or term</li>
</ul>
<a href="http://presshive.com/plugins/wordpress-blog-post-calendar-plugin" rel="nofollow ugc">For more information or to request additional features, please visit the plugin page</a>

Blog Post Calendar Widget

The Blog Posts Calendar Widget allows you to display your archived or future posts in a calendar as a sidebar widget.

Convert Post Types vs Blog Post Calendar Widget