WooCommerce Stamps.com API
Stamps.com API integration for label printing. Requires server SOAP support. If you are using USPS shipping services, then this extension is the perfect choice for you. It can create USPS shipping labels. Stamps.com API access to USPS shipping rates to create labels, though these rates won’t be shown to customers at checkout, for that you need to install USPS Shipping Methods extension in your store.