You probably don’t need ReCAPTCHA
We did everything to avoid using CAPTCHA because spammers on our platform could defeat CAPTCHA anyway. Oftentimes, they're real, actual humans.Hidden inputs, honeypots, etc. None of them worked long-term.Our solution: focus on the content.All content now runs through the following filters, and takes care of 99.9% of spam:
1) Auto-approve any and all content immediately, unless:
  a) The content contains any HTML (url included). If it does, send it to a moderation queue.
    a1) If the submitter had submitted content previously and gotten approved, auto-approve their content, even if it contains HTML.