The captcha plugin keeps WordPress sites safe from spam and password hacks by requiring a simple test to prove you're human, not a computer.

Simple and Easy CAPTCHA. Protects WordPress forms against spam bots by using a picture based challenge enabling users to solve it quickly and easily

WP Light Captcha is very simple and lightweight captcha plugins for your WordPress site.You can protect unwanted login request from hackers.

Captcha image for registration page, customize according to your theme.