Pirate Ship offers easy USPS shipping with discounts up to 87% off retail...

https://wiki-planet.win/index.php/Does_Pirate_Ship_Have_an_API_for_Custom_Fulfillment_Workflows%3F

Pirate Ship offers easy USPS shipping with discounts up to 87% off retail rates, perfect for small sellers who want simple, low-cost options. Just note they only support email help and don’t offer DHL Express