This plugin detects temporary email addresses like mailinator, not connectable email addresses and helps to keep the userbase and comments clean.
WordPress Fix HTML5 Validation
Moves the gallery shortcode styles to the head so it doesn't break XHTML
validation; allows disabling or modifying the default gallery styles.
Slick contact forms allows you quickly and easily create contact forms for any area on your WordPress site using widgets
A plugin that makes building custom HTML forms by hand easier.
Like the Spartans at Thermopylae, these 300 lines of code are meant to protect your forms from malicious invaders.
This widget will submit your wordpress RSS feed to feedvalidator.org, and check the results to verify your feed is valid.
CiteKite automatically validates quotations you make of other websites and lets the world know you care.
Safe Signup Form is a WordPress Plugin that will forward a form submission to an email address, while preventing most automated attacks.
Check the doctype validity using W3c validator (hml , xhtml, ...) when you create or update your page / post / custom post type and show the result in
This plugin displays a bloggers alive.io status to their blog and shows optional messages depending on if the blogger is alive or not.
The Protected Site plugin blocks incoming traffic from accessing a blog or a specific blog in a network by requiring visitors to log in to WordPress.
Adds a new comment validation method in the "Before a comment appears" Discussion subsection panel.
This plugin allows validation of custom fields.
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