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.
Unfortunately it is not possible to make only the "Last Name" field unrequired. If you mark your "Full Name" field as required, the first name and last name both will become a required field. Only "Middle Name" field is optional.
To achieve your requirement, you should add separate textbox fields for first name & last name questions.
Please be noted that it is possible to inject custom css code to place your two separate text boxes next to each other so that it will look like a Full name field. Go ahead and add a separate text box for last name and we will help you with custom css code.