
ALTCHA for sysadmins & developers: a privacy-first, self-hosted CAPTCHA/anti-abuse stack you can actually operate
ALTCHA is an open-source, privacy-centric CAPTCHA that replaces puzzle challenges with a tiny client-side proof-of-work (PoW) and optional adaptive challenges (with audio, i18n, RTL). For production-grade needs, ALTCHA Sentinel adds




















