Amazon/eBay manual inventory leveller

We would like a very simple Java application that creates an interface for a user to adjust quantities between listings on Amazon and eBay. There is a mock-up image attached to the project illustrating what we would like. We want the application to reference a text file that will contain the necessary login and token information for access to both platforms. Once the application is run, it logs in to both sites API and opens the interface that is illustrated in the mock up. Blue shaders are text input fields, gold shaders are buttons. Once the user has input the Seller SKU and eBay Custom Label Field, you click the download button. This will return the following information from both platforms: Item title, Price, and Quantity. Once the user has modified these returned fields as desired, they click upload which will then push the changes to those fields live onto the two respective platforms. After upload is clicked, a pop-up window will appear confirming the upload, clicking OK on this window will then clear the interface for another use. Additionally, if the eBay custom label field is left blank, upon clicking upload, we would like that field to be populated with the Amazon Seller SKU.