Kasuga

Tiny Comment Spam Blocker is a lightweight yet powerful plugin designed to protect your WordPress comments from spam. It employs five different techniques to detect and block unwanted comments:
<ol>
<li>Nonce Verification – Ensures that the comment form submission is genuine.</li>
<li>Submission Time Check – Blocks comments submitted too quickly to prevent bots.</li>
<li>Honeypot Field – Hidden field that traps automated spam bots.</li>
<li>User Agent Validation – Detects suspicious User-Agent strings and blocks them.</li>
<li>Forbidden Word Filtering – Blocks submissions containing words or phrases from a configurable list within the comment body, email address, or IP address.</li>
<li>JavaScript-Based Human Interaction Detection – Sets a verification token when mouse movement, scrolling, or touch interaction is detected.</li>
<li>(Option) Block Non-Japanese Comments – Blocks comments that do not contain Japanese characters (Hiragana, Katakana, or Han/Kanji), primarily targeting machine-translated or foreign spam.</li>
</ol>
These filters are applied in order: if a comment passes the first check, it proceeds to the second, and so on, until all checks are applied or the comment is blocked.
Additional features:
<ul>
<li>Option to log detected spam in a local log file (up to 1.0 MB).</li>
<li>Optional email notifications when spam is detected.</li>
<li>Easy settings page in the WordPress admin panel.</li>
</ul>
<h3>Settings</h3>
The plugin provides the following settings in the WordPress admin panel:
<ul>
<li>Enable Spam Protection – Toggle the spam protection on or off. When disabled, all anti-spam checks are skipped.</li>
<li>Save Spam Detection Log – Enable or disable logging of detected spam. Logs are saved in a local file up to 1.0 MB within the WordPress uploads directory.</li>
<li>Notification Email Address – Enter an email address to receive notifications when spam is detected. Leave blank to disable email notifications.</li>
<li>Minimum Submission Time (seconds) – Set the minimum allowed time between loading the comment form and submitting a comment. Comments submitted faster than this threshold are considered spam.</li>
<li>Forbidden Words List – Enter one forbidden word, phrase, or IP address per line. Submissions containing these entries in the comment body, email address, or IP address will be blocked. Case is insensitive.
<ul>
<li>Example: 
viagra 
online pharmacy 
spam@email.com 
164.138.205.72</li>
</ul>
</li>
<li>Block No Japanese Comments – If enabled, this becomes the final check: Comments that contain Japanese characters (Hiragana, Katakana, or Kanji) will be automatically accepted after passing other security checks. Comments without Japanese characters will be blocked.</li>
</ul>
<h3>Arbitrary Section</h3>
This plugin is designed to be lightweight and fast, ensuring minimal impact on site performance while providing robust protection against comment spam.

Tiny Comment Spam Blocker

A simple and lightweight yet rock-solid plugin that blocks comment spam using multiple automatic detection methods.

Jeff Starr

<blockquote>
✨ Trap bad bots in a virtual black hole
</blockquote>
Important: Do NOT use this plugin on sites with caching. <a href="https://wordpress.org/support/topic/important-do-not-use-on-sites-with-caching/" rel="ugc">Learn more »</a>
👾 Bye bye bad bots..
Bad bots are the worst. They do all sorts of nasty stuff and waste server resources. The Blackhole plugin helps to stop bad bots and save precious resources for legit visitors.
👾 How does it work?
First the plugin adds a hidden trigger link to the footer of your pages. You then add a line to your robots.txt file that forbids all bots from following the hidden link. Bots that then ignore or disobey your robots rules will crawl the link and fall into the trap. Once trapped, bad bots are denied further access to your WordPress site.
I call it the “one-strike” rule: bots have one chance to obey your site’s robots.txt rule. Failure to comply results in immediate banishment. The best part is that the Blackhole only affects bad bots: human users never see the hidden link, and good bots obey the robots rules in the first place. Win-win! 🙂
<blockquote>
✨ Add a blackhole trap to help stop bad bots
</blockquote>
Important: Do NOT use this plugin on sites with caching. <a href="https://wordpress.org/support/topic/important-do-not-use-on-sites-with-caching/" rel="ugc">Learn more »</a>
👾 Features
<ul>
<li>Easy to set up</li>
<li>Squeaky clean code</li>
<li>Focused and modular</li>
<li>Lightweight, fast and flexible</li>
<li>Built with the WordPress API</li>
<li>Works with other security plugins</li>
<li>Easy to reset the list of bad bots</li>
<li>Easy to delete any bot from the list</li>
<li>Regularly updated and “future proof”</li>
<li>Blackhole link includes “nofollow” attribute</li>
<li>Plugin options configurable via settings screen</li>
<li>Works silently behind the scenes to protect your site</li>
<li>Whitelists all major search engines to never block</li>
<li>Focused on flexibility, performance, and security</li>
<li>Email alerts with WHOIS lookup for blocked bots</li>
<li>Complete inline documentation via the Help tab</li>
<li>Provides setting to whitelist any IP addresses</li>
<li>Customize the message displayed to bad bots 😉</li>
<li>One-click restore the plugin default options</li>
<li>Does NOT use or require any .htaccess rules</li>
</ul>
Blackhole for Bad Bots protects your site against bad bots, spammers, scrapers, scanners, and other automated threats.
<blockquote>
✨ Not using WordPress? Check out the <a href="https://perishablepress.com/blackhole-bad-bots/" rel="nofollow ugc">standalone PHP version of Blackhole</a>!
</blockquote>
👾 Whitelist
By default, this plugin does NOT block any of the major search engines (user agents):
<ul>
<li>AOL.com</li>
<li>Baidu</li>
<li>Bingbot/MSN</li>
<li>DuckDuckGo</li>
<li>Googlebot</li>
<li>Teoma</li>
<li>Yahoo!</li>
<li>Yandex</li>
</ul>
These search engines (and all of their myriad variations) are whitelisted via user agent. So are a bunch of other “useful” bots. They always are allowed full access to your site, even if they disobey your robots.txt rules. This list can be customized in the plugin settings. For a complete list of whitelisted bots, visit the Help tab in the plugin settings (under “Whitelist Settings”).
<blockquote>
✨ Check out <a href="https://plugin-planet.com/blackhole-pro/" rel="nofollow ugc">Blackhole Pro</a> and level up with advanced features!
</blockquote>
👾 Exclusive Pro Features
<ul>
<li>Option to disable for logged-in users</li>
<li>Threshold control (number of allowed hits)</li>
<li>Custom email alerts</li>
<li>Custom messages for blocked bots</li>
<li>Custom redirect for blocked bots</li>
<li>Custom blackhole trigger links</li>
<li>Complete inline documentation</li>
<li>Block bots based on user agent</li>
<li>Block bots based on IP address</li>
<li>Whitelist/allow bots by user agent</li>
<li>Whitelist/allow bots by IP address</li>
<li>Redirect whitelisted bots</li>
<li>Set custom HTTP Status Code</li>
<li>Full-featured Bad Bot Log with paging, sorting, and field search</li>
<li>Manually add bad bots to the Bad Bot Log</li>
<li>Geo/IP location lookups for each bad bot</li>
<li>Logs number of blocked hits for each bot</li>
</ul>
..plus everything the free version can do and more.
<blockquote>
✨ Learn more and <a href="https://plugin-planet.com/blackhole-pro/" rel="nofollow ugc">get Blackhole Pro »</a>
</blockquote>
👾 Privacy
User Data: This plugin automatically blocks bad bots. When bad bots fall into the trap, their IP address, user agent, and other request data are stored in the WP database. No other user data is collected by this plugin. At any time, the administrator may delete all saved data via the plugin settings.
Services: This plugin does not connect to any third-party locations or services.
Cookies: This plugin does not set any cookies.
Credit: Header Image Courtesy NASA/JPL-Caltech.
Blackhole for Bad Bots is developed and maintained by <a href="https://x.com/perishable" rel="nofollow ugc">Jeff Starr</a>, 15-year <a href="https://plugin-planet.com/" rel="nofollow ugc">WordPress developer</a> and <a href="https://books.perishablepress.com/" rel="nofollow ugc">book author</a>.
👾 Support development
I develop and maintain this free plugin with love for the WordPress community. To show support, you can <a href="https://monzillamedia.com/donate.html" rel="nofollow ugc">make a donation</a> or purchase one of my books:
<ul>
<li><a href="https://wp-tao.com/" rel="nofollow ugc">The Tao of WordPress</a></li>
<li><a href="https://digwp.com/" rel="nofollow ugc">Digging into WordPress</a></li>
<li><a href="https://htaccessbook.com/" rel="nofollow ugc">.htaccess made easy</a></li>
<li><a href="https://wp-tao.com/wordpress-themes-book/" rel="nofollow ugc">WordPress Themes In Depth</a></li>
<li><a href="https://books.perishablepress.com/downloads/wizards-collection-sql-recipes-wordpress/" rel="nofollow ugc">Wizard’s SQL Recipes for WordPress</a></li>
</ul>
And/or purchase one of my premium WordPress plugins:
<ul>
<li><a href="https://plugin-planet.com/bbq-pro/" rel="nofollow ugc">BBQ Pro</a> – Blazing fast WordPress firewall</li>
<li><a href="https://plugin-planet.com/blackhole-pro/" rel="nofollow ugc">Blackhole Pro</a> – Automatically block bad bots</li>
<li><a href="https://plugin-planet.com/banhammer-pro/" rel="nofollow ugc">Banhammer Pro</a> – Monitor traffic and ban the bad guys</li>
<li><a href="https://plugin-planet.com/ga-google-analytics-pro/" rel="nofollow ugc">GA Google Analytics Pro</a> – Connect WordPress to Google Analytics</li>
<li><a href="https://plugin-planet.com/head-meta-pro/" rel="nofollow ugc">Head Meta Pro</a> – Ultimate Meta Tags for WordPress</li>
<li><a href="https://plugin-planet.com/rest-pro-tools/" rel="nofollow ugc">REST Pro Tools</a> – Awesome tools for managing the WP REST API</li>
<li><a href="https://plugin-planet.com/simple-ajax-chat-pro/" rel="nofollow ugc">Simple Ajax Chat Pro</a> – Unlimited chat rooms</li>
<li><a href="https://plugin-planet.com/usp-pro/" rel="nofollow ugc">USP Pro</a> – Unlimited front-end forms</li>
</ul>
Links, tweets and likes also appreciated. Thank you! 🙂

Blackhole for Bad Bots

Отличный инструмент

Simple. I install this every time I spin up a new WordPress site.

Simple

Blackhole is a WordPress security plugin that detects and traps bad bots in a virtual black hole, where they are denied access to your entire site.

Tiny Comment Spam Blocker vs Blackhole for Bad Bots