Who pays duties and taxes, the seller or the buyer?

It depends on the Incoterm. Under DDP (Delivered Duty Paid), the seller covers all duties, taxes, and clearance, customers pay nothing extra. Under DAP, the buyer pays on delivery, causing surprise charges. For e-commerce, DDP is strongly recommended. Swap ships DDP from your existing 3PLs with duties and taxes prepaid at checkout, so customers never face unexpected charges.