Experience Using PirateShip for International Shipping?

Hi there! I'm working on a client's web design and she is interested in Pirate Ship due to their good customer service and affordable rates. However, she is hoping to ship internationally and is wondering if anyone else has had a good experience with them in this way? I did a little research and it appears they can integrate with Squarespace but I know ShipStation is the preferred tool here. If not, she'd love any other feedback about other international shipping tools and recs you have! Thank you so much. :-)