Need UPS and USPS Help

I need to find the best way to link my current WP site to UPS and USPS so that shipping is automatically calculated.

I have done some research and found that you need licenses and the API links to their systems for this.

Are there no free options for WordPress? I believe that Magento had free options, but can’t find the same for WP.

If I do have to purchase, I would probably buy a multi-site license. So, if I NEED to buy, what are my best options.

I appreciate the help.