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.
Unfortunately, we do not have an option to block the form sharing. You may consider adding some text to the form to explain that the form is only for invited members.
If you need any further assistance, please let us know.