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.
I'm afraid that is not currently possible.
There might be some serious security issues related with such a solution, especially with Cross browser scripting.
However, our Import App can create an Excel template that you can use to populate form responses offline, then update your form submissions by importing all the answers - does this sound like something you can look into?
Looking forward to your response.