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.
This is possible in the online forms, you can choose any of the following methods:
Method 1: Using the Auto Fill feature.
Method 2: Using session ID in the form link, here's a guide: http://www.jotform.com/help/97-How-to-Save-Forms-and-Continue-Later.
I personally prefer method 2.
For the fillable PDF forms, your users can easily fill it out and save the changes, they can then submit it on a later date. To learn more about fillable PDF forms, you can check this guide: http://www.jotform.com/help/312-Fillable-PDF-Everything-you-need-to-know-about-JotForm-Fillable-PDF-Creator
I hope that helps.