You can check Amazon Seller ID & Store URL by ScreenShot

This is your Amazon store URL ▼

This is your seller ID ▼

The Seller ID is used when there are multiple sellers for a product and you want to make sure that shoppers go to the correct link to buy. Once setup correctly.

Login to your Amazon Seller Central account and do the following: 

Select "Settings > Account Info" from the menu. 

Inside of the Seller Account Information, click on 'Your Seller Profile'.

In the Seller Information section there should be a URL for the Storefront Link. The storefront link may look like this: OR => This is store URL

Copy and paste the URL into your browser to go to your storefront.

You can then click into the web browser address bar displaying your URL.

In that URL for the storefront it will now be displaying the full address for your storefront, you will see text similar to marketplaceID=ATVPDKIKX0DER

The last part of the text eg. ATVPDKIKX0DER is the MarketplaceID, don’t include the “marketplaceID=” text before this number

Enter just the ID (not the whole URL or other text) into the MarketplaceID text box. It should look similar to the image below when you have pasted the correct Seller ID in the text box.