CAPTCHA for WordPress that integrates into login, registration and comments.
https://wordpress.org/plugins/wp-math-captcha/
Widgets · CAPTCHA · WordPress Plugins
Get access to data on 29,298 websites that are Math Captcha Customers. We know of 26,823 live websites using Math Captcha and an additional 2,475 sites that used Math Captcha historically and 12,935 websites in the United States.
Get a list of 29,298 websites using Math Captcha which includes location information, hosting data, contact details, 26,823 currently live websites and an additional 14,048 domains that redirect to sites in this list. 2,475 sites that used this technology previously and 12,935 websites in the United States currently using Math Captcha.