Shipmate is described as 'Simple carrier integration - Quickly integrate your eCommerce systems with multiple carriers without the cost or technical headache'. There are five alternatives to Shipmate, not only websites but also apps for a variety of platforms, including Windows, Android, iPhone and Mac. The best alternative is Veeqo. Other great sites and apps similar to Shipmate are Shiptheory (Paid), Scurri (Paid), Courier API (Paid) and ShipStation (Paid).
Scurri is a SaaS carrier management platform. Integrated into multiple channels such as Magento, Brightpearl and more. Scurri is fully integrated into 38 carriers such as UPS, DHL, DPD, TNT, Royal Mail, Yodel and many more.