Felix Arntz

The plugin adds two taxonomies to the WordPress media library which are then available to categorize and tag your attachments. By default, these taxonomies, although sharing the same names and behavior, are separate from the default post taxonomies, but this can easily be changed if desired.
The plugin follows WordPress Core principles and offers a lightweight alternative to similar approaches which often tend to be incredibly flexible, but at the same time complicated and bloated. And if you have a little knowledge of code, you should be able to adjust the plugin exactly to your needs if the default configuration doesn’t satisfy you.
<h4>Features</h4>
<ul>
<li>Adds categories and tags to the Media Library (independent from the regular post categories and tags)</li>
<li>Inserts filter dropdowns for attachment taxonomies into the media toolbar and media modal</li>
<li>Allows to pick taxonomy terms for attachments from within the Attachment Selection & Edit modals</li>
<li>Adds a setting for the default attachment category</li>
<li>Enhances the <code>[gallery]</code> shortcode so that images of a specific attachment taxonomy can be included automatically</li>
</ul>
<h4>Quality attributes</h4>
<ul>
<li>Lightweight plugin following WordPress Core principles</li>
<li>“Decisions, not Options”</li>
<li>Can easily be used as a must-use plugin</li>
<li>Provides a flexible API to add other attachment taxonomies or disable the existing ones for developers</li>
<li>Provides an easy-to-use <code>has_default</code> argument that can be used when registering an attachment taxonomy in order to automatically add a setting for the default taxonomy term</li>
</ul>

Attachment Taxonomies

Works perfect!

Now this is a piece of art!  No bloat, no hassle.  Well done Felix!

Piece of Art

This plugin adds categories and tags to the WordPress media library - lightweight and developer-friendly.

WPExplorer

Post Types Unlimited is an easy way to add custom post types and custom taxonomies to your WordPress site (the right way). The plugin works with any theme and is easily translatable. With Post Types Unlimited you can:
<ul>
<li>Create custom post types.</li>
<li>Create custom taxonomies.</li>
</ul>
Post Types Unlimited makes use of core WordPress functionality for the admin screens and post type, taxonomy registration. This means the plugin is fast, slim and uses the familiar WordPress UI.
Additionally you won’t find any upsell or advertisements in the plugin because there isn’t a “Pro” version. It’s the perfect plugin for adding post types and/or taxonomies to any site (including your client sites) without worrying about extra bloat or annoying ads.
The design of your post types and taxonomies created with the Post Types Unlimited plugin are controlled by your theme. The plugin doesn’t do any hacking or advanced modifications to your templates and thus works great with ANY theme.
If you are using our amazing <a href="https://totalwptheme.com/" rel="nofollow ugc">Total WordPress Theme</a> you will have access to many extra settings that will give you full control over the display of your post types and taxonomies.
This plugin doesn’t have any upsells, banners or other marketing strategies. This makes it perfect for use with any site, including client websites.

Post Types Unlimited

Create unlimited custom post types and custom taxonomies.

Attachment Taxonomies vs Post Types Unlimited