ALTCHA for WordPress

Tip

ALTCHA Plugin version 2 is now available, offering improved protection and enhanced reliability. An upgrade is recommended for all users.

This repository contains the offical ALTCHA plugin for WordPress version 1.

For the new version 2, see github.com/altcha-org/altcha-wordpress-next repository.

What's new in version 2:

• Effective: blocks 99% of spam and abuse attempts
• Invisible for users: frictionless protection, no puzzles or CAPTCHAs
• Works everywhere: plugin-agnostic Request Interceptor integrates with any form plugin
• Handles heavy traffic: stay online with Under Attack Mode
• Stops abuse at scale: firewall and rate limiting included
• Privacy-first: 100% GDPR-compliant and fully accessible

Learn more | Migration guide

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

Read more about ALTCHA: https://github.com/altcha-org/altcha

Website: https://altcha.org

WordPress Plugin Directory: https://wordpress.org/plugins/altcha-spam-protection/

Having troubles? Please report in Issues.

Supported Integrations

• CoBlocks
• Contact Form 7
• Elementor Pro Forms
• Enfold Theme
• Formidable Forms
• Forminator
• GravityForms
• HTML Forms
• WPDiscuz
• WPForms
• WP-Members
• WordPress Login, Register, Password reset
• WordPress Comments
• WooCommerce
• Custom HTML (with a short code [altcha])

Floating UI

The plugin supports the Floating UI but with known limitations:

Currently the Floating UI does not work with:

• Forminator with multi-step forms

Installation

In your WordPress installation, search for "altcha" in the plugin directory and click Install. Alternatively, install the plugin manually:

1. Download the .zip from the Releases.
2. Upload altcha folder to the /wp-content/plugins/ directory
3. Activate the plugin through the 'Plugins' menu in WordPress
4. Review the settings and enable your integrations

Free Mode

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.

REST API

This plugin requires the WordPress REST API. If you are using any "Disable REST API" plugins, ensure that the endpoint /altcha/v1/challenge is allowed.

Hooks

The plugin provides several hooks to customize or extend its functionality.

Filters

• apply_filters('altcha_challenge_url', $challenge_url)
  Override the challenge URL.
  Returns: string

• apply_filters('altcha_integrations', $integrations)
  Modify the list of available integrations. Supported values: captcha, captcha_spamfilter, shortcode.
  Returns: array<string>

• apply_filters('altcha_plugin_active', false, $name)
  Check if an integration by $name is active.
  Returns: bool

• apply_filters('altcha_widget_attrs', $attrs, $mode, $language, $name)
  Override widget attributes.
  Returns: array<string, mixed>

• apply_filters('altcha_widget_html', $html, $mode, $language, $name)
  Override the entire widget HTML.
  Returns: string

• apply_filters('altcha_translations', $translations, $language)
  Override translation strings.
  Returns: array<string, string>

Actions

• do_action('altcha_verify_result', $result)
  Triggered after payload verification.

  • $result: bool verification result.

  • Full server verification payload is available via:

    AltchaPlugin::$instance->spamfilter_result

License

GPLv2