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.
May I know how you are using the form? If you have a website or web server, you can easily create a web page and embed the form instead. With that, the URL your users need to visit is your website page, not the JotForm form URL.
Here's a guide on how to embed your form on a web page: http://www.jotform.com/help/34-Adding-a-Form-to-a-Web-Page.
If you want to use a custom domain for the form URL, that should be possible, but you'll still need to have your own website and hosting. Here's a guide about it: http://www.jotform.com/help/144-How-to-use-Custom-Domains-with-Jotform. Please do note that HTTPS (SSL) is not supported.
Last possible solution is to use the form's full source code, download the files and host it in your own server. However, this is quite tricky and we cannot guarantee that the form will work 100% if you made extensive changes on the source code.
I hope that helps.