We use Advanced Shipping Manager for our shopify store and it's incredibly customizable. More importantly, their team worked hand-in-hand with us to create custom rulesets that aren't natively available. Reasonable price and amazing customer service. Review collected by and hosted on G2.com.

Pretty basic layout/UI, but this by no means stops you from using the platform as it's an incredibly powerful tool. I would like to see the user interface updated/refreshed a bit, but this is simply a wishlist item -- not a necessity. Review collected by and hosted on G2.com.