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.
Proton has one
It appears that proton's is only for them and they don't offer it to other websites unfortunately
Yeah... Probably eventually knowing them, sadly not yet
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:
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.
Yes, the Honeypot system, an invisible part, only visible for bots, they use it and get blocked. easy.
I would argue that's not a CAPTCHA at all, since it's not a Turing test, but rather a browser inspection.
In any case, Cloudflare services like these are not remotely privacy-friendly.
Whatever you pick, please be thoughtful about your use of captchas and try to avoid subjecting people to them frequently.
Probably FriendlyCaptcha and mCaptcha. Proton is also developing their own captcha, but I'm not familiar with it.
Captchas are obsolete novadays, current AI and even bots solve them better than any human. To avoid spam they are useless more and more, better as done by some forums, they simply wait 30-45 minutes before sending the activation mail, no spambot with an 15 minute mail will recieve it. Another one is the honeypot system to block bots.
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.
Roll your own
Heard of POW captcha before, maybe worth a search
Privacy has become a very important issue in modern society, with companies and governments constantly abusing their power, more and more people are waking up to the importance of digital privacy.
In this community everyone is welcome to post links and discuss topics related to privacy.
much thanks to @gary_host_laptop for the logo design :)