JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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.
You can indeed set your form to accept only unique submissions. This check can also be set to a field within your form:
Set this option to an email field within your form and it will only allow for one submission per email address.
If you have any further questions, let us know and we will be happy to help.