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.

GravityKit

This Gravity Forms add-on blocks spam using a non-obtrusive anti-spam measure and can email a spam report summary.
<h3>Spam blocking for Gravity Forms</h3>
To get started, all you need to do is activate the plugin!
<h3>Is the Gravity Forms honeypot field not working for you? 🍯 🐝</h3>
Zero Spam is better than the Gravity Forms anti-spam honeypot field. If you’re getting spammed, try this plugin.
<h3>Use this plugin instead of reCaptcha</h3>
reCaptcha is user-hostile! Use this instead! Users don’t need to click stoplights, crosswalks, or bicycles when you use this plugin to stop spam.
<h3>Enable or disable filtering per form</h3>
If you only want the plugin for specific forms, that’s possible! The plugin adds a simple “Prevent spam using Gravity Forms Zero Spam” setting to each form (requires Gravity Forms 2.5 or newer).
<h3>Spam report emails</h3>
Spam summary report emails are disabled by default. Once enabled, a spam summary that includes the number of entries per-form will be sent via email.
Choose whether you want to be notified after the number of entries reaches a threshold (e.g. 10 spam entries) or after a certain number of days (e.g. every week). If there are no spam entries, no report will be sent.
Requires <a href="https://www.gravityforms.com/?partner_id=1210629&irgwc=1&utm_medium=affiliate&utm_campaign=1210629&utm_source=Katz%20Web%20Services%2C%20Inc." rel="nofollow ugc">Gravity Forms</a>.
Brought to you by <a href="https://www.gravitykit.com?utm_source=plugin&utm_campaign=zero-spam&utm_content=readme" rel="nofollow ugc">GravityKit</a>. We create essential Gravity Forms Add-Ons.

Gravity Forms Zero Spam

It helps way more than Gravity Forms' built in features, and it's nice to try invisible options before making users deal with Captcha quizzes. :)

Appreciate this plugin a lot!

Besides its simple approach, David Walsh’s “Zero Spam” technique, it works well.

Simple and effective

An amazingly simple yet successful strategy, this plugin captures pretty much all automated spam with little chance of false positives. No need to bother people with nasty CAPTCHAs, just install this plugin enjoy the ensuing peace.

Sends automated spam to the bit bucket

Enhance your Gravity Forms to include anti-spam measures originally based on the work of David Walsh's "Zero Spam" technique.

Tiny Comment Spam Blocker vs Gravity Forms Zero Spam