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.
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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, JotForm does not have a password-protect feature at the moment.
You may want to do another approach for this by using Conditionals to hide all the fields when the right code is entered on a textbox.
Please refer to my colleague's suggestion on this thread on how to do it.