There are 2 repositories under shipping-software topic.
The Open Source Shipping dashboard for karrio
Universal Shipping API Node library (Canada Post, DHL, FedEx, UPS, Purolator and more)
Universal Shipping API PHP library (Canada Post, DHL, FedEx, UPS, Purolator and more)
Universal Shipping API Python library (Canada Post, DHL, FedEx, UPS, Purolator and more)
SendCloud API client library for PHP. SendCloud is a European shipping software for e-commerce.