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The simplicity of it is logic defying. It used to be that you had to find crosswalks or move puzzle pieces or type blurred letters and numbers, but NOW all the sudden I can just click a box and HEY!, I'm human?
That's hardly the Turing Test I'd expected.
https://blog.cloudflare.com/turnstile-private-captcha-alternative/
TL:DR cloudflare made a new recaptcha which does some complex math and other stuff on your browser, which done once has no noticable effect but if someone were to scrape websites at an absurd speed it slows everything down significantly.
this is not only cool because you don't have to manually solve the captcha, but also because it allows for low-speed scraping to be feasible, with tools like flaresolverr
Oh, so it's Hashcash; cool to see that idea getting real use.