Hi All,
Just wanted to let the Shopify Community know that we are currently finalizing a new Shopify app. The Shipping Rate Importer app allows you to import your carrier rates to Shopify through a direct Sendcloud api connection or a csv upload. More direct API options are coming soon. We are currently looking for beta testers, if you are interested, please fill in the below form 
https://beta.shipping-rate-importer.com/
Some more information about the Shipping Rate Importer shopify app.
This tool allows you to import and structure your shipping rates from multiple carriers, and easily export them to your Shopify store
- Import your carrier rates through direct API imports or through a .csv file.
- Filter which carriers and countries to export to Shopify and show on your checkout.
- Adjust shipping prices and set variable prices, round prices or add a markup margin.
- Create and review shipping profiles before exporting, and disable individual rates for specific regions or countries based on your needs.
- Select your products and locations, and export them to your store in one click!
- Periodic fetching of carrier rates through setup APIs to make sure you’re up-to-date
- The importer can send you detailed reports of shipping cost changes