Chasil

Universal Star Rating provides shortcodes to give the author the opportunity to add ratings/reviews for desired data, products and services with the aid of a classic star rating system. You can make use of these shortcodes to embed a single inline star rating or a tabular list of star ratings.
To insert a single inline star rating inside a post just type <code>[usr 5]</code> where 5 is the rating/amount of stars.
To insert a tabular list of star ratings inside a post just type <code>[usrlist "Pizza:3" "Ice Cream:3.5" (...)]</code> where the first value is what you want to rate and the second value is the rating/amount of stars. Your list should consist of more than 1 key:value pairs.
<h3>Translations</h3>
Note: This plugin is localized / translatable. This is very important for all users worldwide. So please contribute your language to the plugin to make it even more useful. See <a href="https://translate.wordpress.org/projects/wp-plugins/universal-star-rating" rel="nofollow ugc">Translations</a>

Universal Star Rating

USR provides shortcodes to give the author the opportunity to add ratings for desired products and services with the aid of a star rating system.

JS Morisset

Includes a 5 Star Rating in Schema markup:
<ol>
<li>If the Schema markup does not have an ‘aggregateRating’ property.</li>
<li>If Google allows an ‘aggregateRating’ property for that Schema type.</li>
</ol>
Google allows an ‘aggregateRating’ property for these Schema types and their sub-types:
<ul>
<li>Book</li>
<li>Course</li>
<li>Event</li>
<li>HowTo (includes Recipe)</li>
<li>LocalBusiness</li>
<li>Movie</li>
<li>Product</li>
<li>SoftwareApplication</li>
</ul>
If the Schema type in the Document SSO metabox is not one of these types (or one of their sub-types), then a 5 star rating cannot be added, as doing so would trigger an error in the Google search console. <a href="https://developers.google.com/search/docs/advanced/structured-data/review-snippet" rel="nofollow ugc">See Google’s Review snippet documentation for additional information.</a>

<h3>WPSSO Add Five Stars is a Fallback Solution</h3>
The Google’s Review Snippet technical guidelines reminds us to:
<blockquote>
<a href="https://developers.google.com/search/docs/advanced/structured-data/review-snippet#technical-guidelines" rel="nofollow ugc">Make sure the reviews and ratings you mark up are readily available to users from the marked-up page. It must be immediately obvious to users that the page has review content.</a>
</blockquote>
The WPSSO Add Five Stars add-on includes a 5 star rating if the document Schema markup does not already have an ‘aggregateRating’ property. It is always preferable to include actual ratings and reviews from your visitors and/or customers in the webpage. The WPSSO Add Five Stars add-on can be used in combination with any of the following third-party plugins and service APIs, or the <a href="https://wordpress.org/plugins/wpsso-ratings-and-reviews/" rel="ugc">WPSSO Ratings and Reviews</a> add-on.
Suggested Rating and Review Plugins and Services:
The <a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WPSSO Core plugin</a> supports a selection of plugins that provide ratings and reviews:
<ul>
<li>WP-PostRatings</li>
<li>WP Product Review</li>
<li>Yotpo Social Reviews for WooCommerce</li>
<li>WooCommerce</li>
<li><a href="https://wordpress.org/plugins/wpsso-ratings-and-reviews/" rel="ugc">WPSSO Ratings and Reviews</a></li>
</ul>
The <a href="https://wpsso.com/" rel="nofollow ugc">WPSSO Core Premium plugin</a> also supports a selection of remote service APIs that provide ratings and reviews:
<ul>
<li>Judge.me (Ratings and Reviews)</li>
<li>Shopper Approved (Ratings and Reviews)</li>
<li>Stamped.io (Ratings and Reviews)</li>
</ul>
<h3>WPSSO Core Required</h3>
WPSSO Add Five Stars is an add-on for the <a href="https://wordpress.org/plugins/wpsso/" rel="ugc">WPSSO Core plugin</a>, which creates extensive and complete structured data to present your content at its best for social sites and search results – no matter how URLs are shared, reshared, messaged, posted, embedded, or crawled.

WPSSO Add Five Stars for Google Rich Snippets

Add a 5 star rating and review from the site organization if the Schema markup does not already have an 'aggregateRating' property.

Universal Star Rating vs WPSSO Add Five Stars for Google Rich Snippets