CAPTCHA Solution does not work alone and is intended to work with other plugins. It is originally created for [Contact Form 7], however, you can use it with your own plugin. Note: This product is “really simple” as its name suggests, i.e., it is not strongly secure. If you need perfect security, you should try other solutions. How does it work? CAPTCHA Solution does not use PHP “Sessions” for storing states, unlike many other PHP CAPTCHA solutions, but stores them as temporary files. This allows you to embed it into WordPress without worrying about conflicts.