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 use the Hide/Show condition on your form, with a text box field to show the rest of your form only when a specific code has been entered into that box.
You would use a form collapse to show/hide all your fields.
Please view a sample form here, the code is test123:
I hope this helps, please inform us if you need further assistance.