Can forms be used offline?

Web version of the form cannot be used offline.  However, if the form is a smaller basic form, you can create a fillable PDF version of the form that can be filled out offline and submitted when back online:

https://www.jotform.com/help/312-JotForm-Fillable-PDF-Creator-With-All-Points

The are limitations on fillable PDF versions as described in the above guide.