Peter

<p>Stop a lot of spambots from polluting your site by making visitors identify a random word displayed as an image before commenting and optionally before registering. You can customize the pool of words to display.</p>
<h4>Features</h4>
<ul>
<li>
<p>Toggle whether registered users need to enter the word</p>
</li>
<li>
<p>Random font display</p>
</li>
<li>
<p>No cookies required</p>
</li>
<li>
<p>No JavaScript required</p>
</li>
<li>
<p>Auto-generated audio for visually impaired users</p>
</li>
<li>
<p>Easy-to-read</p>
</li>
<li>
<p>No mapping of words from the code — words are used once or removed after 24 hours</p>
</li>
<li>
<p>Reminder of what was entered if you get the word wrong</p>
</li>
<li>
<p>Selective blocking of trackbacks, pingbacks</p>
</li>
<li>
<p>Easy to translate</p>
</li>
<li>
<p>Compatible with caching plugins</p>
</li>
</ul>
<h4>Negatives</h4>
<ul>
<li>
<p>Purposely no obscuring techniques so that the anti-spam word is easy to read</p>
</li>
<li>
<p>The more people who use this plugin, the more motivation for spambots to target it</p>
</li>
</ul>
<h4>Requirements</h4>
<ul>
<li>
<p>GD Library and FreeType Library (There’s a diagnostic page to tell you whether you have them installed. If needed, just ask your web host to install them!)</p>
</li>
<li>
<p>WordPress 3.2 or higher</p>
</li>
</ul>
<h4>Translations</h4>
<ul>
<li>ru_RU translation by koc</li>
<li>sk_SK translation by Patrik Žec (PATWIST) of http://patwist.com</li>
</ul>


Peter’s Custom Anti-Spam

Stop a lot of spambots from polluting your site by making visitors identify a custom word displayed as an image before commenting.

Daniel

<p><strong>This is ALTCHA Plugin version 1.</strong></p>
<p><strong>ALTCHA Plugin version 2 is now available, offering improved protection and enhanced reliability. An upgrade is recommended for all users.</strong></p>
<p><a href="https://altcha.org/docs/v2/wordpress" rel="nofollow ugc">Learn more</a> | <a href="https://altcha.org/docs/v2/wordpress/install" rel="nofollow ugc">Installation guide</a> | <a href="https://altcha.org/docs/v2/wordpress/migrating-from-v1/" rel="nofollow ugc">Migration guide</a></p>
<p>What’s new in version 2:</p>
<ul>
<li><strong>Effective</strong>: blocks 99% of spam and abuse attempts</li>
<li><strong>Invisible for users</strong>: frictionless protection, no puzzles or CAPTCHAs</li>
<li><strong>Works everywhere</strong>: plugin-agnostic <a href="https://altcha.org/docs/v2/wordpress/features/#request-interceptor--works-everywhere" rel="nofollow ugc">Request Interceptor</a> integrates with any form plugin</li>
<li><strong>Handles heavy traffic</strong>: stay online with <a href="https://altcha.org/docs/v2/wordpress/features/#under-attack-mode--stay-online-under-pressure" rel="nofollow ugc">Under Attack Mode</a></li>
<li><strong>Stops abuse at scale</strong>: firewall and rate limiting included</li>
<li><strong>Privacy-first</strong>: 100% GDPR-compliant and fully accessible</li>
<li><strong>Unlimited</strong>: no external services, unlimited verifications</li>
</ul>
<p>Learn more about ALTCHA at <a href="https://altcha.org" rel="nofollow ugc">altcha.org</a>.</p>
<p><a href="https://altcha.org" rel="nofollow ugc">ALTCHA</a> provides a free, open-source Captcha alternative utilizing a proof-of-work mechanism to safeguard your website against spam and unwanted content. Our anti-spam solution ensures robust spam protection without compromising user privacy.</p>
<p>Unlike other solutions, ALTCHA is free, open-source, and self-hosted. It operates independently without external services, avoids the use of cookies and fingerprinting, refrains from user tracking, and maintains full compliance with GDPR regulations.</p>
<h3>Free Mode</h3>
<p>The free self-hosted mode is enabled by default after installation. No additional setup is required, except enabling the integrations you need in the plugin settings.</p>
<h3>Privacy</h3>
<h4>No cookies, no tracking</h4>
<p>ALTCHA prioritizes user privacy by avoiding the use of cookies and fingerprinting techniques.</p>
<h4>No external service</h4>
<p>Operating in Self-hosted mode (the default setting), this plugin remains fully contained within your WordPress installation, eliminating any reliance on external services. You can opt-in for our SaaS version to utilize the Spam Filter API. For more information visit https://altcha.org.</p>
<h3>Modes of Operation</h3>
<p>This plugin operates in two modes, you can select which mode you want in the settings (see API Region):</p>
<ul>
<li>Self-hosted – free, fully self-contained without external services.</li>
<li>Custom or SaaS API – requires a server such as <a href="https://altcha.org/docs/v2/sentinel/" rel="nofollow ugc">ALTCHA Sentinel</a>.</li>
</ul>
<h3>REST API</h3>
<p>This plugin requires the WordPress REST API. If you are using any “Disable REST API” plugins, ensure that the endpoint <code>/altcha/v1/challenge</code> is allowed.</p>
<h3>Supported Integrations</h3>
<ul>
<li>CoBlocks</li>
<li>Contact Form 7</li>
<li>Elementor Pro Forms</li>
<li>Enfold Theme</li>
<li>Formidable Forms</li>
<li>Forminator</li>
<li>GravityForms</li>
<li>HTML Forms</li>
<li>WPDiscuz</li>
<li>WPForms</li>
<li>WP-Members</li>
<li>WordPress Login, Register, Password reset</li>
<li>WordPress Comments</li>
<li>WooCommerce</li>
<li>Custom HTML (with a short code <code>[altcha]</code>)</li>
</ul>
<h3>Source Code</h3>
<p>All source code for the plugin, and the ALTCHA widget is available on GitHub. In the repository, you’ll also find versions of non-minified JavaScript and CSS assets:</p>
<ul>
<li>Plugin: https://github.com/altcha-org/wordpress-plugin</li>
<li>ALTCHA Widget: https://github.com/altcha-org/altcha</li>
</ul>
<h3>Terms of Service And Privacy Policy for SaaS</h3>
<ul>
<li>Privacy Policy: https://altcha.org/privacy-policy</li>
<li>Terms of Service: https://altcha.org/terms-of-service</li>
</ul>


ALTCHA Spam Protection


ALTCHA is a free, open-source Captcha alternative. It uses a proof-of-work mechanism to protect your website from spam and unwanted content. Unlike other solutions, ALTCHA is self-hosted, avoids cookies and tracking, and is fully GDPR compliant. It also features a powerful spam filter that integrates seamlessly with your WordPress site. With options for self-hosted and external service modes, ALTCHA offers flexibility and robust protection for any WordPress site.


ALTCHA: Free, Open-Source Captcha Alternative with Robust Spam Protection


I've installed ALTCHA on a non-WordPress website a little under a year ago, and it's been protecting that website from spam registrations (these were an issue there!) ever since.



Now I'm using it on a couple WordPress websites as well, and it seems to work just as fine, albeit it's only been a few days.



If you've ever been annoyed by having to repeatedly select busses or fire hydrants, or move parrots around, and you don't want to push that experience onto your visitors,  ALTCHA can be the solution. It's non-intrusive to normal users (the calculation performed only takes a couple seconds), but is a great way to deter spammers, who would rather automatically submit a few hundred forms than spend that same amount of CPU time on a calculation required to only submit that one form on your page.



Oh, and I love that this plugin is open source and no-nonsense. It will never clutter your WordPress UI with calls to upgrade to pro or notifications about Black Friday sales. It adds a single sub-menu item under Settings, and is very civil in all regards. And it also respects your visitor privacy: no data will be transmitted to other servers than yours by default due to having it installed, unless you explicitly configure it to use ALTCHA's cloud API, which adds some extra functionality in addition to filtering out bots.



All that said, it's not a silver bullet of course, and you may want to keep Akismet enabled too as a second line of defence.


Great self-contained spam protection


Altcha v1 was brilliant - did just what I wanted seamlessly.  Sadly when I installed v2 the login blocked for some users (and it was impossible to see why).  I think the increased comms to the central system were to blame, but I'm not sure.  I can't switch back to v1 without having the 'nag' to upgrade constantly visible on the plugin page, and putting the shortcode back into all the forms.  A quick switch to Cloudfare Turnstile and all is working nicely.  Sad, though, because Altcha looked great.


v1 was great; v2 - I had to uninstall

ALTCHA offers a free, open-source Captcha alternative, ensuring robust spam protection while respecting user privacy and GDPR compliance.

Peter’s Custom Anti-Spam vs ALTCHA Spam Protection