İs it possıble to allow Multiple Coupon for Customers

I need to allow customers to use multiple coupons, how can I do this.

I'm having to do this as a work around to the very inflexible shipping options. 

I want to provide a flat fee for shipping for all of my products except 1 which has free shipping. How can I do this?

As far as I understand from your thread you want to add multiple coupon code for one submission. I am sorry to say that it is not possible with Jotform.

If you want to provide free shipping just for one item you can make the arrangements as you see below:

If you have any question or issues, please do not hesitate contacting us. We will be glad to assist you.