What is JotForm?
JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
We believe that if one user has a question, there could be more users who may have the same question. This is why many of our support forum threads are public and available to be searched and viewed. If you’d like help immediately, feel free to search for a similar question, or submit your question or concern.
Unfortunately, there is not a way to block an IP address from submitting your form, you could only limit the submissions based on the number allowed from an IP address or based on a form question.
Here're the guides that will help you with this:
If you have embedded your form in a website then you could implement a custom script as well to block the website when the IP address is used.