msfreed

Thin Content Manager helps you easily identify thin content pages (i.e. posts and pages with minimal textual content) on your site and block them from search engines. The plugin calculates the body word count for each post/page on your site (disregarding words contained within HTML tags and shortcodes) and displays the information on a new ‘Thin Content Manager’ page within the Settings section of your WordPress admin panel. The admin page then provides a simple point-and-click interface to automatically insert robots noindex and nofollow tags – <meta name=”robots” content=”noindex, nofollow”> – into the head section of pages you select. These tags tell Google and other search engine spiders to ignore those pages, which is important for improving your site’s quality score and trust ranking for SEO purposes.
This plugin works with with single site installs only.

Thin Content Manager

See the body word count to identify pages with thin content, then select pages to insert robots noindex,nofollow tags into.

Payadl

BT Captcha – simple, Bilingual, Flexible, Protect Your WP Blog Against Comment Spams 
Special thanks to the developer of <a href="https://wordpress.org/extend/plugins/anti-captcha/" rel="ugc">Anti Captcha</a> Plugin

BT Captcha

BT Captcha - simple, Bilingual, Flexible, Protect Your WP Blog Against Comment Spams

Thin Content Manager vs BT Captcha