Actually! We do offer a web interface for this exact thing. Many of our customers are small businesses who don't have developers to integrate the API, so we built a dashboard for them to compare shipping prices, print labels, and track shipments. (You can also use it even if you're not a business)
You can see a small gif of it working under "How you make money" in the interview. https://cdn-images-1.medium.com/max/800/1*GDC26ygGdl49WKsb9Z...