Devtard

This plugin automatically searches posts when they are published/imported/saved and adds new taxonomy terms (tags by default) if term names or related keywords from a user-created keyword list are found.
<h4>Features</h4>
<ul>
<li>Compatible with several post import plugins (<a href="https://wordpress.org/plugins/automatic-post-tagger/faq/" rel="ugc">FAQ #4</a>)</li>
<li>Supports custom taxonomies and post types; for example, APT is able to categorize posts (<a href="https://wordpress.org/plugins/automatic-post-tagger/faq/" rel="ugc">FAQ #6</a>), add tags/categories to WooCommerce products (<a href="https://wordpress.org/plugins/automatic-post-tagger/faq/" rel="ugc">FAQ #7</a>)</li>
<li>Supports UTF-8 characters, non-Latin and logographic alphabets (<a href="https://wordpress.org/plugins/automatic-post-tagger/faq/" rel="ugc">FAQ #5</a>), including Arabic, Chinese, Cyrillic etc.</li>
<li>Bulk tagging tool (with a scheduler) for processing multiple posts</li>
<li>Import/Export tools (CSV & JSON format support)</li>
<li>Configuration groups with custom rules for selected keyword sets; wildcard (regex) support for related keywords</li>
</ul>
See <a href="https://wordpress.org/plugins/automatic-post-tagger/screenshots/" rel="ugc">Screenshots</a> and <a href="https://wordpress.org/plugins/automatic-post-tagger/faq/" rel="ugc">FAQ</a> for more information.

Automatic Post Tagger

Adds relevant taxonomy terms to posts using a keyword list provided by the user.

Muhammad Junaid Iqbal

WP Auto Tagging is a free WordPress plugin to automatically add tags for WordPress posts. Please note that Plugin is under construction and it is its first release. I will keep it updating with passage of time & you should keep in touch for bugs and problems you find in plugin. WP Auto Tagging works best for small & big blog owners.
Note:- I will not answer to any question on WordPress support. Please generate a ticket at www.eibug.com
<ol>
<li>
It will read post title and will split title into Tags and will add tags to all the posts automatically (posts which are missing tags).
</li>
<li>
You do not need to manually insert tags for each post.
</li>
<li>
Install WP Auto Tagging WordPress Plugin, Activate it and tags will be added to all already published posts.
</li>
<li>
WP Auto Tagging will add tags to new posts automatically as well (post you are going to publish now).
</li>
<li>
WP Auto Tagging supports only One word tag.
</li>
<li>
Plugin will skip words in title less than 4 characters.
</li>
<li>
Plugin will generate and add 6 tags for your published posts, you can delete unwanted tags and can update post.
</li>
<li>
All of the generated and added tags will not be deleted once you de-activate WP Auto Tagging WordPress plugin.
</li>
</ol>
<h3>Arbitrary section</h3>
I needed WP Auto Tagging WordPress Plugin for my HD Wallpapers website with more than 9,000 posts. All of the posts were missing tags and I was missing search traffic. I wanted to add 3-4 tags to all the published posts but it was taking lots of my time. I wanted to write a script which could automatically add 4 wordpress tags for all the published posts. Plugin will not generate and add tags to posts already containing tags.

WP Auto Tagging

WP Auto Tagging Wordpress Plugin Will Automatically Generate & Add Tags to Wordpress Posts.

Automatic Post Tagger vs WP Auto Tagging