Tim van Iersel

Adds custom field to the post & pages editor for custom JSON-ld schema markup also known as structured data. The plugin also validates if the JSON is formated correctly. <a href="http://coderisk.com/wp/plugin/websitescanner-custom-schema/RIPS-8iSfZmxGFd" rel="nofollow ugc"></a>
Add your own JSON-ld on every page, post and custom post without the <code><script></code> to show your own custom Schema markup.
Works well with the following plugins:
<ul>
<li><a href="https://wordpress.org/plugins/remove-schema/" title="Remove Schema WordPress plugin" rel="ugc">Remove Schema</a></li>
</ul>
Usecases:
With the combination of the WordPress plugin it’s easy to overwrite the schema on a specific page. 
If a plugin like Yoast SEO or other plugin or theme that generates schema you can disable the schema and add your own custom schema to the page.

Websitescanner Custom Schema

Adds custom field to the post & pages editor for custom JSON-ld schema markup also known as structured data.

eGrove Systems

SEO Schema – Structured Data & Breadcrumb List plugin helps you add JSON-LD structured data for Organization Schema and Breadcrumb Schema to your WordPress site. It allows you to provide detailed organization information, like name, URL, logo, description, contact details, address, and dynamic breadcrumbs.
Features include:
<ol>
<li>Admin form to input organization details.</li>
<li>Supports Organization Schema (JSON-LD).</li>
<li>Supports dynamic Breadcrumb Schema (JSON-LD).</li>
<li>Add dynamic breadcrumbs with customizable name and URL.</li>
<li>Easy-to-use interface in the WordPress admin panel.</li>
</ol>
<h3>License</h3>
This plugin is licensed under the GPLv2 or later. 
For more details, visit <a href="https://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">GNU General Public License</a>.

SEO Schema – Structured Data & Breadcrumb List

A WordPress plugin to add structured data for Organization Schema and Breadcrumb Schema using JSON-LD.

Websitescanner Custom Schema vs SEO Schema – Structured Data & Breadcrumb List