FCaptcha – A modern CAPTCHA system designed to detect everything (github.com)

FCaptcha has launched an innovative open-source CAPTCHA system aimed at countering a wide range of automated threats, including traditional bots and advanced vision-based AI agents, with either a single click or an invisible mode. This system is notable for its sophisticated detection capabilities, leveraging over 40 behavioral signals, including mouse trajectory, velocity, and even micro-tremor analysis to distinguish between human and bot interactions. It employs a server-verified Proof of Work (PoW) mechanism that not only raises the cost for potential attackers but also scales difficulty based on request patterns, making credential stuffing more resource-intensive. By allowing users to self-host the system without external dependencies and maintaining a strong focus on privacy—free from persistent fingerprinting and cross-site tracking—FCaptcha positions itself as a versatile and transparent alternative to existing solutions like reCAPTCHA. Technically, it offers a variety of implementation options, including support for Go, Python, and Node.js, facilitating integration into diverse tech stacks. This project not only addresses the evolving landscape of automated threats but also opens up opportunities for community contributions in machine learning and integration enhancements, ultimately reinforcing security measures in web applications.