Free, open-source
Captcha alternative
Unlike other solutions, ALTCHA is free, open-source and self-hosted, without external services, does not use cookies nor fingerprinting, does not track users, and is fully compliant with GDPR.
More than just
a Captcha solution
ALTCHA represents a modern, accessible, and inclusive approach to safeguarding websites, APIs, and online services from spam and abuse.
Its fundamentally different approach makes it ideal for businesses constrained by privacy regulations in the EU and around the world.
Compliant with GDPR
Comply with GDPR by using a privacy-first solution that does not use cookies nor fingerprinting and does not track users. Learn more
Friendly to Humans
Say goodbye to tedious puzzle-solving and improve your website's UX by integrating a fully automated proof-or-work mechanism. Try demo
Inclusive to Robots
Get ready for AIs and integrate M2M ALTCHA into your APIs and online services making them accessible to machines. See how
Open source, MIT licensed
ALTCHA is a free, open-source project licensed under a permissive MIT license. Works for everyone - individuals, small businesses and enterprises.
Is it a good Captcha alternative for you?
Read more about ALTCHA’s effectiveness →
Try Captcha verification for humans
ALTCHA’s web component is familiar to users and easy to integrate into any website.
Check the box to get verified.
Try Machine-to-Machine (M2M) ALTCHA
M2M ALTCHA works as a rate-limiter implemented on the consumer’s end. It helps you protect expensive resources, reduce spam and abuse in your online services and APIs while keeping them accessible to automated systems.
Read more about M2M ALTCHA →
<!-- Add <script> tag --><script async defer src="/altcha.js" type="module"></script>
<!-- Use <altcha-widget> tag in your forms --><altcha-widget challengeurl="/api/altcha"></altcha-widget>Refer to the documentation for more details and to see how to integrate with your server.
A privacy-friendly solution to spam control
ALTCHA is an open-source alternative to reCAPTCHA and similar solutions
| ALTCHA | reCAPTCHA | |
|---|---|---|
| Privacy-friendly, GDPR compliant No cookies, no tracking, no external servers. | | |
| Frustration-free No visual puzzles. PoW Captcha is better for people. | | |
| Accessible Works automatically, without requiring user interaction. | | |
| Customizable Adjust the complexity of the PoW and widget branding to your needs. | | |
| Comprehensive All humans and all robots are welcome. M2M ALTCHA can be implemented on any system. | | |
| Open-source Free to use, free to modify. MIT licensed. | | |
ALTCHA is a free open-source project hosted on GitHub. MIT licensed. Feel free to contribute.
Developed as a privacy-respecting alternative to Captcha and other popular solutions, ALTCHA is a better way to shield your website and online services from spam and abuse while protecting your user’s privacy.