Cap: A Lightweight, Privacy-Preserving Open-Source CAPTCHA Alternative

Cap is a lightweight, modern, open-source CAPTCHA alternative using SHA-256 proof-of-work. It's fast, private, and incredibly easy to integrate. Composed of a JavaScript widget (@cap.js/widget) and a server-side component (@cap.js/server), Cap offers various extensions and supports multiple runtimes and programming languages. It even runs standalone in Docker. Compared to hCaptcha, Cap is 250x smaller and, using proof-of-work, requires no user tracking. Fully open-source, Cap offers modes like invisible and floating to suit various needs.