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.
At JotForm, we want to make sure that you’re getting the online form builder help that you need. Our friendly customer support team is available 24/7.
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.
Sorry but this is currently not possible. To better understand why that's the case, please have a look at the reply of one of our Developers on this thread.
That thread above was a canceled feature request due to the reasoning given on his reply. To sum it up, the Unique ID widget generates the ID "after form submission" so there's no way to show it while the user is filling out the form.
And even if we manage to come up with a way to generate it prior to form submission, issues and conflicts would still arise if multiple users open the form and never submitted it in the same order the IDs were generated (thus the impracticality of having such a feature).
As an alternative, if you really need something unique to be displayed on your form "while the user is filling it out", then try the Random Value Generator widget instead.
Here's a quick guide on How-to-Add-a-Widget-to-your-Form
In case you have a followup question, we'd appreciate it if you could give us more info and describe it in detail so we can better assist you.