ALTCHA

Overview

ALTCHA is a privacy-focused, open-source bot protection solution that offers an alternative to traditional CAPTCHA services like reCAPTCHA or hCaptcha. Instead of relying on behavioral tracking, third-party cookies, or image recognition puzzles, ALTCHA uses cryptographic proof-of-work challenges that the visitor's browser solves computationally. This approach verifies human visitors without collecting personal data or depending on external tracking infrastructure.

What This Script Does

ALTCHA's scripts present a computational proof-of-work challenge when a visitor encounters a protected form or action. The visitor's browser performs a series of cryptographic calculations to solve the challenge, and the solution is submitted to the server for verification. This process typically takes a fraction of a second for a human visitor's device but is computationally expensive for bots attempting to submit at scale. The scripts do not set tracking cookies, collect personal data, or make requests to third-party services. All verification can be processed entirely on your own server, keeping the interaction between the visitor's browser and your infrastructure. No fingerprinting, behavioral profiling, or cross-site tracking is involved.

Consent & Compliance

ALTCHA is designed with privacy compliance as a core feature. It does not set cookies, collect personal data, or communicate with third-party servers. The proof-of-work challenge is a purely computational verification that does not involve tracking or profiling visitors. Under GDPR, ePrivacy, and similar frameworks, ALTCHA's scripts qualify as strictly necessary for the security function they provide — protecting forms from automated abuse. The open-source nature of the project allows complete auditability of its privacy claims.

Should You Block This Without Consent?

No. ALTCHA provides essential bot protection functionality without setting cookies or collecting personal data. Its proof-of-work approach is privacy-preserving by design and qualifies as a strictly necessary security measure.