At a Glance:
Private Captcha is a self-hostable, privacy-first Proof-of-Work CAPTCHA service with an adaptive difficulty system and a lightweight customizable widget, designed as an open alternative to Google reCAPTCHA, hCaptcha, and Cloudflare Turnstile.
Overview:
Private Captcha is an independent, self-hostable CAPTCHA service that uses a Proof-of-Work mechanism to distinguish between human users and bots. It is built with a specific focus on user privacy, GDPR compliance, and on-premises deployment, avoiding the collection of personally identifiable information or behavioral tracking data. The project is designed to provide a stable, backward-compatible API while remaining sustainable through a managed SaaS offering. It offers an adaptive challenge difficulty system that allows for fine-grained configuration, and ships with a lightweight, customizable widget that includes an invisible version.
Key Decision Points:
Deployment model: Designed for self-hosting, providing an on-premises CAPTCHA solution without external dependencies on third-party services.
Privacy architecture: Explicitly avoids behavior tracking and the processing of personally identifiable information, with a stated focus on GDPR compliance.
Widget options: Includes both customizable and "invisible" widget variants, allowing site owners to balance user experience with security requirements.
Project sustainability: Financially supported through a managed SaaS offering, with a stated goal of long-term survival and continued development.
Core Features:
Adaptive challenge difficulty: Supports various configuration options to scale the difficulty of challenges based on the perceived threat level.
Optimized backend: Engineered for low resource consumption and high throughput, specifically avoiding JavaScript on the backend to maintain low latency.
Lightweight, customizable widget: Provides a client-side widget that can be visually customized, with an "invisible" mode that requires minimal user interaction.
Usage statistics: Includes a backend module for tracking and reviewing CAPTCHA usage metrics.
Proof-of-Work mechanism: Relies on computational puzzles to deter bots, including AI scrapers, without user identification.
Use Cases:
Privacy-conscious site operators: Deploy a CAPTCHA solution that aligns with strict privacy policies and GDPR requirements by avoiding personal data collection.
Developers seeking a self-hosted bot-mitigation tool: Integrate a backend-optimized, API-driven CAPTCHA service directly into an on-premises infrastructure.
Sites currently using cloud-based CAPTCHAs: Replace services like Google reCAPTCHA or Cloudflare Turnstile with a self-hosted alternative that does not track visitors.
Open-Source Alternative Value:
Private Captcha operates as a self-hosted, open alternative to major CAPTCHA services, specifically naming Google reCAPTCHA, hCaptcha, and Cloudflare Turnstile as its targets. Its main value proposition lies in its ability to run entirely on a user's own infrastructure, with a backend optimized for low latency and high throughput. The project's commitment to a privacy-centric model—processing no PII and performing no behavior tracking—is supported by its technical design, not just a policy. It is sustained by a managed SaaS offering, which is intended to support its long-term development as an independent, open-source project.
