basically what the title says
the ones i’m aware of:
- google’s recaptcha
cloudflare’shcaptcha
cloudflare being better for privacy compared to google, but still not great afaik
mCaptcha can be self hosted https://mcaptcha.org/
It’s technically not a CAPTCHA, for the pedantic, but it serves teh same purpose.
Not sure about captchas but the honeypot filter works fine.
Its open source so there probably is a good level of privacy.
The only privacy-friendly CAPTCHA is a self-hosted one.
The only user-friendly kind is none at all.
Depending on the web site, an alternative bot-filtering strategy might make sense, such as:
- Allowing signup without a CAPTCHA, but requiring one before the first post/upload is allowed.
- Allowing signup without a CAPTCHA, but deleting accounts that behave like bots.
- Allowing signup without a CAPTCHA, but deleting accounts that don’t purchase something.
- Allowing login without a CAPTCHA, but restricting retry rates and/or locking accounts after 10+ failures.
Cloudflare’s Turnstile has an invisible mode that you’re probably using in a lot of places and aren’t aware of it. It provides an invisible challenge to the browser and requires no interaction. I would say no input require in quite user-friendly.
Cloudflare’s CAPTCHA is Turnstile. I’ve found it very useful. It doesn’t use pick the image or type the text, it’s just tick the box. You can even set it to invisible, then the user doesn’t need to even do that, the challenge is sent to the browser and is completed automatically.
https://developers.cloudflare.com/turnstile/
In terms of privacy, it’s is still Cloudflare, but at least it’s not intrusive to the user experience.
Probably FriendlyCaptcha and mCaptcha. Proton is also developing their own captcha, but I’m not familiar with it.
