https://github.com/tiagozip/cap

The privacy-first, self-hosted CAPTCHA for the modern web.
https://github.com/tiagozip/cap

anti-abuse anti-bot anti-scraper antispam bun captcha defense hashcash javascript proof-of-work turing-test web

Last synced: 1 day ago
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The privacy-first, self-hosted CAPTCHA for the modern web.

• Host: GitHub
• URL: https://github.com/tiagozip/cap
• Owner: tiagozip
• License: other
• Created: 2025-01-11T17:35:52.000Z (over 1 year ago)
• Default Branch: main
• Last Pushed: 2026-04-16T18:16:46.000Z (6 days ago)
• Last Synced: 2026-04-16T20:23:21.673Z (6 days ago)
• Topics: anti-abuse, anti-bot, anti-scraper, antispam, bun, captcha, defense, hashcash, javascript, proof-of-work, turing-test, web
• Language: JavaScript
• Homepage: http://capjs.js.org/
• Size: 10.5 MB
• Stars: 5,220
• Watchers: 14
• Forks: 366
• Open Issues: 8
• Metadata Files:
  • Readme: README.md
  • Contributing: CONTRIBUTING.md
  • License: LICENSE
  • Security: SECURITY.MD

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• awesome-starred - tiagozip/cap - The privacy-first, self-hosted CAPTCHA for the modern web. (JavaScript)

README

          
#  Cap

Cap is a lightweight, modern open-source CAPTCHA alternative using SHA-256 proof-of-work and JavaScript instrumentation challenges. It's fast, private, and extremely simple to integrate.



## Documentation

**[Read the docs](https://capjs.js.org)**, try the [demo](https://capjs.js.org/guide/demo.html) or read the [feature comparison](https://capjs.js.org/guide/alternatives.html)

## What is Cap?

Cap replaces visual captchas with modern, accessible and privacy-preserving proof-of-work challenges. No images, no tracking, no dependencies, works everywhere.

You can either run it on any JavaScript runtime, or use the standalone mode with Docker. [Learn more about how Cap works](https://capjs.js.org/guide/)

## Why Cap?

- **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

- **Programmatic**  

   Hide Cap's widget and solve challenges in the background

- **M2M**  

   Keep your APIs protected while accessible to friendly robots

- **Open-source**  

   Completely free & open-source under the Apache 2.0 license

Cap is a great alternative to [reCAPTCHA](https://www.google.com/recaptcha/about/), [hCaptcha](https://www.hcaptcha.com/) and [Cloudflare Turnstile](https://developers.cloudflare.com/turnstile/)

## License

This project is licensed under the Apache-2.0 License, please see the [LICENSE](https://github.com/tiagozip/cap/blob/main/LICENSE) file for details.

Copyright ©2025 - present [tiago](https://tiago.zip)

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[![OpenSSF Best Practices](https://www.bestpractices.dev/projects/9920/badge?v=gold)](https://www.bestpractices.dev/projects/9920) [![](https://data.jsdelivr.com/v1/package/npm/@cap.js/wasm/badge)](https://www.jsdelivr.com/package/npm/@cap.js/wasm)