The Peninsula Group has released a series (http://tinyurl.com/hhylq8t) of free macOS-compatible drivers that support thermal printer manufacturers including Zebra, Datamax, Honeywell and Brady with the goal of making it easier to print labels.
Using web based shipping services form companies like UPS, FedEx and DHL is now possible; even Amazon FBA is supported. You can print readable barcodes, text and images from any website or application.