ALTCHA
ALTCHA is an open-source CAPTCHA alternative that uses proof-of-work challenges for bot protection. Its scripts present computational puzzles to verify human visitors without setting tracking cookies, collecting personal data, or relying on third-party services.
Is ALTCHA GDPR compliant?
ConsentStack classifies ALTCHA's trackers as essential (strictly necessary), so its banner does not block them. That is our classification, not a legal ruling. The exemption from prior consent comes from the ePrivacy Directive (Article 5(3)) and covers only what is strictly necessary for a service the visitor asked for, and the GDPR still governs any personal data, such as an IP address, sent to ALTCHA. List ALTCHA in your cookie policy and privacy notice so visitors know it is there.
- Consent required
- Generally exempt, classified strictly necessary
- Consent category
- essential
- Tracker domain
- altcha.org
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.
Consent Categories
Also Known As
Industries
Tracked Domains (1)
altcha.orgEssentialaltcha.org is an essential domain operated by ALTCHA, used to keep the site working, including security, load balancing, and sessions.
Frequently Asked Questions
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Manage consent for ALTCHA
ConsentStack automatically detects and manages ALTCHA trackers so your site stays compliant with global privacy regulations.