OpenPorte Spam Protection

OpenPorte is a free and open-source plugin that protects WordPress forms
from spam using a lightweight Proof-of-Work challenge instead of CAPTCHAs.
The goal is to make spam expensive for bots while keeping the experience almost
invisible for legitimate visitors and respecting their privacy.

For site owners, OpenPorte offers an easy to configure and deploy modern
spam protection under their control.
For the site users, it offers an accessible, transparent and privacy-friendly
alternative to CAPTCHAs.

OpenPorte is built around the open-source ALTCHA widget.

Some highlights:

• CAPTCHA-free spam protection
• Fully open source (GPL)
• Self-hosted – no mandatory external service
• Designed to be accessible and privacy-friendly
• Compatible with existing ALTCHA integrations
• Easy migration for users of ALTCHA Spam Protection v1 (≤ 1.26.3)

For the list of contributors, refer to our GitHub project: Contributors.

AI-assisted development

AI-assisted project. Architecture, security decisions, and final review are
mine; AI tools (Claude, Mistral, and others) help with drafting code, tests,
translations, and documentation — without them, one person couldn’t keep
this fork alive.

Background

The original ALTCHA Spam Protection WordPress plugin (v1) was open source
(GPLv2). Its authors have since released a version 2/3 which is no longer
open source. They no longer maintain the open source project and recommend
that users migrate to v2/v3. See the official project at https://altcha.org
for their offering.

OpenPorte started as a fork and continues the v1 line as free software
(GPLv2 or later) for users who want to stay on a fully open-source,
self-hosted solution. It is a faithful fork: existing v1 installations
can switch to OpenPorte and keep their settings (see Upgrading).

Compatibility

OpenPorte is backward-compatible with ALTCHA Spam Protection v1 plugin:

• Your existing settings are migrated automatically on activation.
• The [altcha] shortcode keeps working (alongside the new [openporte]).
• The altcha_* filters and actions keep firing as deprecated aliases.
• Custom API Mode has been verified against GateCHA,
  an open source server implementing the creation and verification of ALTCHA challenges.

See the Deprecations section for the full list of compatibility aliases and
what they map to.

Upgrading

Read the full description on the official page →