Mercari Price Checker

Check matching listings and prices from Mercari Japan on e-commerce product pages

Mercari Price Checker instantly helps you compare e-commerce prices with second-hand and authentic listings from Mercari Japan (https://jp.mercari.com). When viewing products on Amazon (Amazon.co.jp or Amazon.com), the extension automatically analyzes the product name, strips unnecessary retailer noise, and places a discreet badge near the price. Clicking the badge slides open an in-page sidebar displaying live Mercari listings complete with thumbnail images, prices in Japanese Yen (¥), and direct links to product pages. Key Features: Automatic Product Detection: Cleanly extracts product titles and core model numbers (e.g. phones, headphones, consoles, apparel). On-Page Floating Badge: Shows real-time Mercari status and lowest available prices without displacing web page layouts. In-Page Slide-Out Drawer: Isolated with Shadow DOM to ensure zero styling conflicts with the host website. Direct Navigation: Clicking any item opens its full listing page on Mercari Japan in a new tab. Toolbar Action Popup: Search Mercari manually anytime and toggle the extension on or off. How to Use: Navigate to any Amazon product page (e.g. iPhone, Sony headphones, Nintendo Switch). Look for the floating "Mercari" badge near the product title. Click the badge to open the sidebar with current Mercari Japan listings. Click any item card to open the listing directly on jp.mercari.com. Use the toolbar extension icon for quick manual searches or to toggle on/off. Privacy & Security: This extension operates locally inside your browser. No personal data, browsing history, or account credentials are collected, stored, or sent to third-party tracking servers. Requests are strictly sent directly to Mercari Japan to retrieve public listing search results. Disclaimer: "This is an independent personal project and is not an official product of, nor affiliated with or endorsed by, Mercari, Inc."