Self-hosted CAPTCHA that ditches annoying puzzles for SHA-256 proof-of-work challenges - 250x smaller than hCaptcha, zero tracking, works everywhere

Tired of forcing users to click traffic lights and crosswalks just to prove they’re human? Cap flips the CAPTCHA game by using computational proof-of-work instead of visual puzzles. Your visitors’ browsers do a bit of SHA-256 math in the background while they never see another blurry street sign again. It’s like mining cryptocurrency, but actually useful.

At just ~20kb with zero dependencies, Cap loads 250x faster than hCaptcha and doesn’t phone home with user data. You can self-host it on any JavaScript runtime or spin up the Docker container for standalone mode with analytics. The proof-of-work approach means legitimate users sail through while bots get computational homework - no more accessibility nightmares or privacy invasions.

With 5,100+ stars and growing fast, Cap is positioning itself as the modern alternative to reCAPTCHA and friends. The Apache 2.0 license means you can deploy it anywhere, customize the UI with CSS variables, or even run it headless for API protection. If you’re building anything user-facing and hate making people solve puzzles, this deserves a star.

⭐ Stars: 5102
💻 Language: JavaScript
🔗 Repository: tiagozip/cap