Pirate Ship offers easy USPS discounts up to 87%, making it great for sellers...

https://record-wiki.win/index.php/I_Sell_on_Etsy_and_Shopify_%E2%80%94_Should_I_Stop_Using_Pirate_Ship%3F

Pirate Ship offers easy USPS discounts up to 87%, making it great for sellers who ship mostly with USPS. Just note, their support is email-only, which might slow you down if you need quick answers