Doltics

Simple validation for your website.
Our validation API checks and ensures the content processes on your website is valid. 
We validate email records against the domain to ensure that you are receiving and sending valid content from your site using out third party solution. 
We check and verify the email domain MX records are valid. Each new unique request is maintained for 24 hours before a fresh request is done.
<ol>
<li><a href="https://doltics.com/docs/email-validation-api/" rel="nofollow ugc">Documentation</a></li>
<li><a href="https://doltics.com/terms-of-service/" rel="nofollow ugc">Terms of service</a></li>
</ol>
Future plugin updates will include <a href="https://en.wikipedia.org/wiki/Deep_learning" rel="nofollow ugc">Deep learning</a> to better understand spam emails and email content with compatibility with popular form plugins. 
For now we validate the <code>is_email</code> function provided by WordPress core.

Doltics Validator

Roland Rust

It functions as a frontend for the Markup Validator Web Service API on http://validator.w3.org. Stylesheets are checked as well.
Languages available: 
+ english 
+ deutsch(german)

Batch Validator

This plugin performs a batch markup validation check over your entire WordPress website.

Doltics Validator vs Batch Validator