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.
JotForm enables you to adjust the type of files you require. If you click the EXTENSIONS button on the top toolbar. You can add and remove the file extension you wish.
You may also adjust the file size that the user may upload.
Hope this helps.
Glad to hear that my colleague's suggestion helped.
Just to add, you can also refer to this guide for future reference: http://www.jotform.com/help/29-Upload-Field-Allowed-File-Types
Should you need any assistance again, feel free to open a new thread here in the forum.