Georgi Popov

This plugin provides a list of similar / related entries to an article or a custom post type entry.
This list could be added in the form of a:
<ol>
<li>Gutenberg Block</li>
<li>Shortcode</li>
<li>Widget</li>
</ol>
If you add a widget to the sidebar it will only appear when on the details view of an entry, as similarity cannot be calculated when on a list page of multiple entries.
The syntax for the shortcode is <code>[magadanski-similar-posts id="" post_type="" taxonomy="" limit=""]</code>
You can use the attributes as follows:
<ol>
<li>ID — (integer) the ID of the post you’d like to get similar posts for. Default value: the current post ID.</li>
<li>post_type — (string) the post type you’d like to query. Default value: “post”.</li>
<li>taxonomy — (string) the taxonomy based on which you’d like to get similar items. Default value: “category”.</li>
<li>limit — (integer) a maximum number of results you’d like to receive. Default value: 5.</li>
</ol>
The similarity is considered based on the number of common categories (or other taxonomy terms) for this post and the rest of the posts in your blog.

M Similar Posts

This plugin lists similar to the current post based on the number of common categories.

RobMarsh

The Post-Plugin Library does nothing by itself but must be installed to provide shared code for the <a href="https://wordpress.org/extend/plugins/similar-posts/" rel="ugc">Similar Posts</a>, <a href="https://wordpress.org/extend/plugins/recent-posts-plugin/" rel="ugc">Recent Posts</a>, <a href="https://wordpress.org/extend/plugins/random-posts-plugin/" rel="ugc">Random Posts</a>, <a href="https://wordpress.org/extend/plugins/popular-posts-plugin/" rel="ugc">Popular Posts</a>, and <a href="https://wordpress.org/extend/plugins/recent-comments-plugin/" rel="ugc">Recent Comments</a> plugins.
<h3>Version History</h3>
<ul>
<li>2.6.2.1
<ul>
<li>support for recent comments to only show one comment per post</li>
<li>fix for donate link</li>
</ul>
</li>
<li>2.6.2.0
<ul>
<li>new {imagealt} output tag — rather like {imagesrc}</li>
<li>{excerpt} can now trim to whole sentences</li>
<li>content filter can now take parameter string</li>
<li>widget can now take parameter string</li>
<li>output can be appended to posts & feeds</li>
</ul>
</li>
<li>2.6.1.0
<ul>
<li>the current post can be marked manually</li>
<li>widgets now honour the option to show no output if list is empty</li>
<li>{commenterlink} now respects the appropriate filter</li>
</ul>
</li>
<li>2.6.0.0
<ul>
<li>version bump to indicate compatibility with WP 2.6</li>
<li>fix to really include attachments</li>
<li>new parameter for {imagesrc} to append a suffix to the image name, e.g. to get the thumbnail for attachments</li>
</ul>
</li>
<li>2.5.0.11
<ul>
<li>new option to include attachments</li>
<li>{php} tag now accepts nested tags</li>
<li>new output tag {authorurl} — permalink to archive of author’s posts</li>
<li>fix for numeric locale issue in Similar Posts</li>
</ul>
</li>
<li>2.5.10
<ul>
<li>new option to select algorithm for term extraction in Similar Posts</li>
<li>new manual links option in Similar Posts</li>
<li>fix for faulty non-English tag indexing in Similar Posts</li>
<li>fix for page selection in old versions of WP</li>
<li>made omit current post try harder to find current post ID</li>
</ul>
</li>
<li>2.5.0.9
<ul>
<li>new option to order Recent Posts by date of last edit rather than date of creation</li>
<li>new option to match the current post’s author</li>
<li>extended options for snippet and excerpt output tags</li>
</ul>
</li>
<li>2.5.0.7
<ul>
<li>new option to show by status, i.e., published/private/draft/future</li>
<li>{categorynames} and {categorylinks} apply ‘single_cat_name’ filter</li>
<li>fixes bug in WP pre-2.2 causing installation code to fail</li>
</ul>
</li>
<li>2.5.0.6
<ul>
<li>bug fix for new option for Recent Comments</li>
</ul>
</li>
<li>2.5.0.5
<ul>
<li>new option for Recent Comments: just_current_post</li>
<li>{snippet} and {commentsnippet} now handle ‘…’</li>
<li>{commentexcerpt} now same parameters as (excerpt}</li>
</ul>
</li>
<li>2.5.0.4
<ul>
<li>{commentpopupurl} targets the correct comment </li>
</ul>
</li>
<li>2.5.0.3
<ul>
<li>bug fix for showing pages when not selected</li>
</ul>
</li>
<li>2.5.0.2
<ul>
<li>{image} tag has even more options</li>
<li>new {commentpopupurl} tag</li>
</ul>
</li>
<li>2.5.0.1
<ul>
<li>made compatible with WP MU</li>
</ul>
</li>
<li>2.5.0
<ul>
<li>{image} has new post, link, and default parameters</li>
<li>new {imagesrc} tag</li>
<li>fix to empty category bug</li>
</ul>
</li>
<li>2.5b28
<ul>
<li>more work on {image} scaling</li>
<li>improvements to Similar Posts matching</li>
<li>experiment with Chinese/Korean/Japanese matching</li>
</ul>
</li>
<li>2.5b27
<ul>
<li>made {image} scaling more robust</li>
</ul>
</li>
<li>2.5b26
<ul>
<li>reverted thumnail serving (speed)</li>
<li>fix current post after extra query</li>
</ul>
</li>
<li>2.5b25
<ul>
<li>option to sort output, group templates</li>
<li>removed ‘trim_before’ option added more logical ‘divider’</li>
<li>{date:raw}, {commentdate:raw}, etc.</li>
<li>fix for {image} resizing when and not </li>
<li>{image} now serves real thumbnails</li>
</ul>
</li>
<li>2.5b24
<ul>
<li>fix for recursive replacement by content filter</li>
<li>fix to {gravatar} to allow for ‘identicon’ etc.</li>
<li>fix to {commenter} to allow trimming</li>
<li>fix a warning in safe mode</li>
</ul>
</li>
<li>2.5b23
<ul>
<li>new option to filter on custom fields</li>
<li>proper nesting of braces in {if} ; also allowed in condition</li>
<li>improved bug report feature</li>
<li>better way to omit user comments</li>
</ul>
</li>
<li>2.5b22
<ul>
<li>show_pages option now possible to show only pages</li>
<li>update for {postviews}</li>
<li>fix {commenterlink} giving no output</li>
</ul>
</li>
<li>2.5b21
<ul>
<li>fix bug in {snippet} stripping</li>
</ul>
</li>
<li>2.5b20
<ul>
<li>fix default behaviour of {gravatar}</li>
</ul>
</li>
<li>2.5b18
<ul>
<li>new tag {if:condition:true:false}</li>
</ul>
</li>
<li>2.5b17
<ul>
<li>enhanced {php}</li>
</ul>
</li>
<li>2.5b16
<ul>
<li>fix submenus to work with Lighter Admin Drop Menu</li>
</ul>
</li>
<li>2.5b15
<ul>
<li>fix bugs, add ‘included posts’ setting</li>
</ul>
</li>
<li>2.5b14
<ul>
<li>enhanced bug reporter</li>
</ul>
</li>
<li>2.5b13
<ul>
<li>added {gravatar}, extended {author}</li>
</ul>
</li>
<li>2.5b11
<ul>
<li>fixed problem with bug reporter</li>
</ul>
</li>
<li>2.5b9
<ul>
<li>clarifying installation instructions</li>
</ul>
</li>
</ul>

Post-Plugin Library

The shared code library for Similar posts, Recent Posts, Random Posts, Popular Posts and Recent Comments.

M Similar Posts vs Post-Plugin Library