diff --git a/README.md b/README.md
index 59c2c31..90c0c1a 100644
--- a/README.md
+++ b/README.md
@@ -253,6 +253,7 @@ Google captchas use cookies to track users and rank their IPs.
 
 <img width="16" src="misc/check.png"> </img>  **Instead use**
 - [hCaptcha](https://www.hcaptcha.com/) - Privacy-first CAPTCHA for web, mobile, and more.
+- [mCaptcha](http://mcaptcha.org/) ([repo](https://github.com/mCaptcha/mCaptcha)) - An open-source CAPTCHA system with seamless UX.  mCaptcha uses SHA256 based proof-of-work (PoW) to rate limit users.
 - [OOPSpam](https://www.oopspam.com/) - No-captcha, privacy-friendly anti-spam, anti-bot API. Requires no personal data for detection. Supports popular platforms like WordPress. Privacy commitment in their mission statement.
 
 ## Commenting Engines