Free, open-source and self-hosted CAPTCHA alternative to reCAPTCHA. Privacy-first and powered by proof-of-work and instrumentation challenges.
See the codeCap is a lightweight, modern open-source CAPTCHA alternative using proof-of-work and instrumentation challenges. It's fast, private, and extremely simple to integrate.
Read the docs, try the demo or deploy on Railway
Cap replaces visual captchas with modern, accessible and privacy-preserving challenges. No images, no tracking, no dependencies, works everywhere.
The default way to use Cap is with the Standalone Docker container. Learn more about how Cap works
250x smaller than hCaptcha
~20kb, zero dependencies, loads in milliseconds
Privacy-first
Cap doesn't send any telemetry back to our servers
Fully customizable
Change the colors, size, position, icons and more with CSS variables
Proof-of-work
Your users no longer have to waste time solving visual puzzles.
Standalone mode
Run Cap anywhere with a Docker container with analytics & more
No user interaction needed
Hide Cap's widget and solve challenges in the background
Open-source
Completely free & open-source under the Apache 2.0 license
Cap is a great alternative to reCAPTCHA, hCaptcha and Cloudflare Turnstile
This project is licensed under the Apache-2.0 License, please see the LICENSE file for details.
Copyright ©2025 - present tiago
(top 24 of 66)
423 followers · starred May 2026
1,472 followers · starred Jun 2025
81 followers · starred May 2025
34 followers · starred Aug 2026
JavaScript
88.4%
CSS
9.2%
Rust
1.6%
Free, open-source and self-hosted CAPTCHA alternative to reCAPTCHA. Privacy-first and powered by proof-of-work and instrumentation challenges.
See the codeCap is a lightweight, modern open-source CAPTCHA alternative using proof-of-work and instrumentation challenges. It's fast, private, and extremely simple to integrate.
Read the docs, try the demo or deploy on Railway
Cap replaces visual captchas with modern, accessible and privacy-preserving challenges. No images, no tracking, no dependencies, works everywhere.
The default way to use Cap is with the Standalone Docker container. Learn more about how Cap works
250x smaller than hCaptcha
~20kb, zero dependencies, loads in milliseconds
Privacy-first
Cap doesn't send any telemetry back to our servers
Fully customizable
Change the colors, size, position, icons and more with CSS variables
Proof-of-work
Your users no longer have to waste time solving visual puzzles.
Standalone mode
Run Cap anywhere with a Docker container with analytics & more
No user interaction needed
Hide Cap's widget and solve challenges in the background
Open-source
Completely free & open-source under the Apache 2.0 license
Cap is a great alternative to reCAPTCHA, hCaptcha and Cloudflare Turnstile
This project is licensed under the Apache-2.0 License, please see the LICENSE file for details.
Copyright ©2025 - present tiago
(top 24 of 66)
423 followers · starred May 2026
1,472 followers · starred Jun 2025
81 followers · starred May 2025
34 followers · starred Aug 2026
JavaScript
88.4%
CSS
9.2%
Rust
1.6%