Pirate Ship offers up to 87% off USPS rates, making it a top pick if you mainly...

https://shipping-discounts.s3.amazonaws.com/goshippo/video/pirateship-shipping-reviews.html

Pirate Ship offers up to 87% off USPS rates, making it a top pick if you mainly ship USPS and want great discounts. Its support is only by email, which might slow things down