Saving form entries to complete them later

I have a form that is very long and will be complete over a period of time. It needs to be saved at regular intervals, then submitted at the very end. Is there a widget or method that I could pass on to the user?

We have the following 'continue later' options.

1. An Autofill option that saves the data locally in user's browser storage. It means that the form user will need to use the same browser to see saved data.

How to Enable Auto Fill Feature

2. A session based save and continue later method. It saves the data on our servers in a session format, so that the session can be accessed from any place. This method requires two forms to be linked.

How to Save Forms to Continue Later

3. A form Submission Edit link. The form users can use it in order to edit submitted entries, so this is more like submit and edit later rather than save and continue later.

How to Let Users Update Their Form Submissions at a Later Date

Note, the 1st and the 2nd methods are not compatible between each other. You can use only one of them on a particular form.