Pirate Ship shines with USPS discounts up to 87% off and easy-to-use free...

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

Pirate Ship shines with USPS discounts up to 87% off and easy-to-use free accounts, but their support is email-only, which can slow things down. Shippo is a better fit if you need faster help or want DHL Express shipping options