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.
We have mobile apps. Those Mobile apps are intended for administration of your Jotform account, forms and submissions. But not the actual filling of the form. I am afraid you cannot use them to fill out the form.
I would suggest you to make your form Mobile responsive, so your user can easily fill the forms on Mobile. Here is the guide, to make your form Mobile responsive: https://www.jotform.com/help/311-How-to-make-forms-mobile-responsive
If you have any query, or need further assistance, feel free to revert back.