Instructions for Sellers to Authorize an Application to Access Their Amazon Seller Account

1. Go here (developer.amazonservices.com)
2. Click the Sign up for MWS button.
3. Log into your Amazon seller account.
4. On the MWS registration page, click the button for I want to use an application to access my Amazon seller account with MWS.
5. In the Application Name text box, type the name of the application that you want to use. This doesn't need to be the exact name; it is merely for your reference in the future.
6. In the Application's Developer Account Number text box, enter the MWS developer account identifier given to you by the application developer (SingleFeed ID # is: 9987-2482-4114).
7. Click the Next button.
8. Accept the Amazon MWS License Agreement and click the Next.
9. Copy your account identifiers (Merchant ID and Marketplace ID). It is also a good practice to print this page and save it in a safe place.
10. Follow the instructions given to you by your application developer to enter your account identifiers into the application.