Get Started with ALTCHA

ALTCHA (“Alternative CAPTCHA”) provides a modern, privacy-focused alternative to reCAPTCHA and other legacy CAPTCHA systems. Instead of relying on intrusive tracking, it uses a proof-of-work mechanism, along with advanced threat detection methods when integrated with ALTCHA Sentinel.

ALTCHA is fully self-hosted, ensuring strong data privacy and compliance with modern regulatory standards.

Why ALTCHA?

• Frictionless experience for most users (no interaction required)
• Effectively blocks advanced bots and abuse
• Privacy-focused: no cookies, no tracking, and GDPR-compliant
• Accessible and WCAG-compliant
• Open-source core for transparency and control
• Lightweight and fast-loading for optimal performance
• Flexible, with developer-friendly integration
• Enhanced protection when combined with ALTCHA Sentinel

Open-Source

The open-source core of ALTCHA allows you to integrate privacy-first bot protection completetely free, without any external services.

1. Widget - JavaScript component that handles proof-of-work verification and user interaction with customizable UI options and lightweight implementation.
2. Libraries - Server-side tools for payload validation and verification, supporting multiple programming languages.

Commercial Products

1. Sentinel Self-Hosted - Self-hosted all-in-one spam protection platform that combines proof-of-work with machine learning and pattern recognition to block abuse while maintaining full privacy compliance. Recommended for production environments requiring robust protection.
2. Cloud - Fully managed, EU-hosted bot protection powered by ALTCHA Sentinel. No infrastructure to run, with adaptive CAPTCHA and privacy-first design built in.
3. WordPress Plugin - Drop-in bot protection for WordPress forms and logins, powered by Sentinel or Cloud.

Find Your Solution

One solution does not fit all, which is why ALTCHA offers a different recommended path depending on who you are and what you need. See the Solutions overview for the full breakdown, or jump straight to your case:

• Individuals — Personal sites, blogs, and side projects. Start with the free open-source widget or the WordPress plugin, and upgrade to ALTCHA Cloud if you need adaptive protection without running a server yourself.
• Businesses — E-commerce, SaaS, marketplaces, and agencies. Stop checkout fraud, fake sign-ups, and credential stuffing with ALTCHA Cloud, a fully managed, EU-hosted service — or self-host with ALTCHA Sentinel if you need full infrastructure control.
• Enterprises — Larger organizations with their own security and infrastructure requirements. ALTCHA Sentinel runs entirely on your infrastructure, with SSO, role-based access, clustering, and SLA-backed support.
• Governments — Public sector and government agencies. ALTCHA Sentinel supports statutory compliance, WCAG-compliant accessibility, data sovereignty, and platform ownership through perpetual licensing.