You might be using captchas to hide content for any or all of the following reasons: –

• to prevent content scraping by bad bots
• to prevent DDOS attack
• to prevent content from problematic networks

It might be protecting your content, however, you may be missing out on SEO rankings.

Based on experience and evidence via authentic resource:

Hiding the content behind captchas is NOT GOOD in SEO perspective. Here is why.

• GoogleBot will index that page but cannot crawl through the content.
• GoogleBot assumes this page is a thin content i-e: nothing but a captcha on it.
• Since it cannot crawl, so don’t expect any rankings.
• If so many pages are getting indexed like this with thin or just captchas, it impacts overall SEO rankings too.

Besides all this above, your website is NOT penalized just for having captcha-driven content, however, you won’t be ranked easily due to inaccessibility to content for algorithms to analyze and rank somewhere.

Wait. It doesn’t mean you should stop using captcha to prevent scraping. Just workaround for GoogleBot (if you’re really concerned with rankings).

Workaround: Serve different version to GoogleBot vs. Users. – This is slightly against Google Policies (falls in cloaking), however, if you do it right, you can still do it. It is confirmed by John Mueller via Google Office Hours SEO Videos (Official Resource).

“From a policy point of view we’re okay with situations where you serve us the full content, and you require a captcha on the user side. If you need to do that slightly differently for Googlebot or maybe other search engines than you would for the average user from our point of view that’s fine.”

John Muller, Google Office Hours (Youtube)

So at your website end, if its GoogleBot, don’t serve captcha at all. If any other BOT or user, present the captcha first.

Another similar example is rendering content via edge worker and its impact on SEO.