The "在庫スコープ-Rakuten-" Chrome extension provides a comprehensive overview of inventory data for all products on Rakuten marketplace. It displays the number of in-stock items (including those not displayed on the site), JAN codes, shipping days, and links to the cheapest listings on Rakuten marketplace, Yahoo! Shopping, and Amazon. This extension allows users to easily track the total inventory and fluctuations across multiple shops for each product, making it easy to gauge price fluctuations, sales volume, and the ability to source products at the lowest price.