# FCaptcha

> Self-hosted, open-source CAPTCHA detecting AI agents and bots with behavioral analysis and proof-of-work. Drop-in replacement for Turnstile, reCAPTCHA, hCaptcha.

- **Category:** Security
- **Licence:** MIT
- **Latest version:** v1.46.1
- **Open source:** oss
- **Languages:** Go, JavaScript, Python
- **Platforms:** Docker, Docker Compose, Go, Node.js, Python, Helm, Fly.io
- **Tags:** Security, Privacy First, Web Security, Captcha, Proof-of-Work, Node.js, Open Source, Go, Python, Self Hosted, Bot Detection, Anti bot, Tls fingerprinting, Behavioral analysis, Ai detection, Invisible captcha, Fingerprinting, Headless Browser Detection, Scraping Protection, Selenium Detector, Playwright Detection, Puppeteer Detection, Ai Bot Detection, Turnstile Alternative, Recaptcha Alternative, Hcaptcha Alternative, Vision AI Detection

## Description

FCaptcha is a self-hosted CAPTCHA system that detects bots, headless browsers, automation frameworks, and vision-based AI agents such as GPT-4V and Claude Computer Use. It uses behavioral biometrics (mouse micro-tremor, keystroke cadence, touch kinematics), environmental fingerprinting (Playwright, Puppeteer, Selenium detection, CDP artifacts, TLS JA3/JA4), and server-verified SHA-256 proof-of-work challenges. The widget offers checkbox or invisible modes and serves drop-in compatible siteverify endpoints for Turnstile, reCAPTCHA, and hCaptcha so migration is a base-URL change. It runs as a single container (Go, Python, or Node.js) with optional Redis for multi-replica state sharing. No cookies, no third-party data, no persistent fingerprinting. Licensed MIT.

## Links

- [Homepage](https://github.com/WebDecoy/FCaptcha)
- [Website](https://webdecoy.com/product/fcaptcha/)
- [Docker](ghcr.io/webdecoy/fcaptcha)
- [Demo](https://webdecoy.com/product/fcaptcha-demo/)
- [GitHub Repository](https://github.com/WebDecoy/FCaptcha)
- [Documentation](https://docs.webdecoy.com/)
- [Installation Guide](https://github.com/WebDecoy/FCaptcha/blob/main/INSTALLATION.md)
- [Docker Guide](https://github.com/WebDecoy/FCaptcha/blob/main/docker/README.md)

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Source: https://selfhost.directory/project/fcaptcha