Pirate Ship offers big savings on USPS labels—up to 87% off—with easy, no-fee...

https://mike-wiki.win/index.php/Does_Shippo_Have_a_REST_API_I_Can_Use_for_Shipping_Automation%3F

Pirate Ship offers big savings on USPS labels—up to 87% off—with easy, no-fee shipping and quick support. It’s perfect if you mainly use USPS and want a straightforward setup