To offer a wide selection of carriers we do not integrate directly with carriers but with shipping platforms that do. This offers both a superior experience to customers and merchants in terms of reliability. Costs for shipping labels are billed directly to your account at one of these platforms.
The way our prepaid return labels work is the following:
You sign up for an account with one of our supported label-platforms: EasyPost, Shippo, ShipStation
See the available platforms and carriers over here: Supported Carriersโ
You can
either connect your own carrier-contract to these platforms