Pirate Ship offers great USPS discounts—up to 87% off—and easy label printing,...

https://magic-wiki.win/index.php/Shippo_for_Amazon_and_eBay:_Can_It_Manage_Both_Channels%3F

Pirate Ship offers great USPS discounts—up to 87% off—and easy label printing, making it perfect for sellers who ship mostly with USPS. But if you need DHL Express or prefer chat support over email only, Shippo might be a better fit