Vladimir Prelovac

WP Nofollow Categories is a SEO plugin which adds nofollow attribute to all category links throughout the blog. It will also add noindex tag to category page and nofollow author links. This will effectively remove the category pages from SEO point of view.
The goal is to flow the page rank to other pages on your site like posts and tags while avoiding duplicate content issue.
Plugin by <a href="http://www.prelovac.com/vladimir" rel="nofollow ugc">Vladimir Prelovac</a>.
<h3>Credits</h3>
Thanks to <a href="http://kempwire.com/" rel="nofollow ugc">Jonathan Kemp</a> whose <a href="https://wordpress.org/extend/plugins/nofollow-categories/" rel="ugc">plugin</a> inspired me
<h3>License</h3>
This file is part of WP Nofollow Categories.
WP Nofollow Categories is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version.
WP Nofollow Categories is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
You should have received a copy of the GNU General Public License along with WP Nofollow Categories. If not, see <a href="http://www.gnu.org/licenses/" rel="nofollow ugc">http://www.gnu.org/licenses/</a>.

WP Nofollow Categories

Nofollows category links across the site. Adds Noindex to category pages.

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.

WP Nofollow Categories vs Automatic Post Tagger