Pirate Ship offers USPS rates up to 87% off, making it a solid choice if you...

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

Pirate Ship offers USPS rates up to 87% off, making it a solid choice if you mostly ship domestically with USPS. Support is email-only, which might slow things down during busy times