Free, open-source
Captcha alternative
Unlike other solutions, ALTCHA is free, open-source and self-hosted, does not use cookies nor fingerprinting, does not track users, and is fully compliant with GDPR.
More than just
a Captcha protection
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.
GDPR Compliant
Comply with GDPR by using a privacy-first solution that does not use cookies nor fingerprinting and does not track users. Learn more
Complete Spam Protection
Utilize the proof-of-work mechanism as the initial line of defense. Then, stop even sophisticated attacks and human-generated spam with the Spam Filter.
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. Visit GitHub
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.
Spam Filter
ALTCHA’s GDPR-compliant Spam Filter provides an additional protective layer by analyzing incoming data through natural language processing and machine learning, distinguishing between legitimate data and spam.
Now available for integration on your website. For Free!
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 →
ALTCHA API is a SaaS platform allowing you to integrate quickly. It’s available for free to anyone without registration.
Refer to the documentation for more details about integration.
ALTCHA is an open-source project allowing you to self-host it without reliance on external services.
Refer to the documentation for more details and to see how to integrate with your server.
Examples
See example setups of ALTCHA with different front-end frameworks:
Official Libraries
ALTCHA’s TypeScript library runs everywhere! Whether it’s modern browsers, Node.js, Bun, Deno, or any WinterCG-compatible runtime.
Plugins
Visit the Integrations documentation for more community-developed libraries and plugins.
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. | | |
| Spam Filtering Employs machine learning to categorize submitted data and identify unwanted messages. | | |
| Open-source Free to use, free to modify. MIT licensed. | | |
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