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.
Here's a demo where a different section of the form is shown depending on the selection made in a drop down. A Show/Hide condition was created for each selection:
It's also possible to have thank you page to which the user is redirected upon submission of the form vary depending on the selection made in the drop down, as explained by my manager Jeanette in this thread. Is this the type of functionality you meant? If not, please elaborate.