DOOM Captcha - Captchas don't have to be boring
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hCaptcha - Do you use a captcha to keep out bots? hCaptcha is a drop-in replacement for reCAPTCHA that earns website owners money and helps companies get their data labeled.
Humans Not Invited - CAPTCHA that filters out humans and only lets programs pass
StormX - Earn crypto while you shop at your favorite stores