Captcha CK

IP filtering

List the IP that you want to block and deny the ability to submit your forms

Mathematical check

Ask your visitor to make a small calculation. As this is a visual check rendered by an image, a basic robot will not be able to read it
Use the option to set the text color

Time check

Setup the time you think your visitor shall spend before sending the form, if it is sent too fast, it's a robot

Hidden field check

This is a honeypot, no human will fill it, so if it is checked, it's a robot

No hidden cost, you can use it as many time as you want.