CardScope

CardScope is a browser extension for Chrome that provides price analytics and portfolio tracking for Cardmarket sellers. You can see at a glance how card prices are developing, manage your inventory more efficiently and find the best buying and selling times.

The extension reads the publicly visible price data directly from Cardmarket and calculates trends, average prices and price fluctuations. You can add individual cards to a watchlist and get notified when the price drops below a threshold you set.

For sellers managing larger inventories, CardScope offers a portfolio overview. You can see the estimated total value of your inventory and how the value changes over time.

CardScope was built for all players and collectors who are active on Cardmarket: whether Magic: The Gathering, Pokémon, Yu-Gi-Oh! or other trading card games. The extension supports all card games available on Cardmarket.

As soon as you open a Cardmarket page, CardScope automatically detects whether you are viewing a single card page, a search results page or your own portfolio.

On single card pages you see a price panel with the current average price, the lowest and highest offer, the price trend of the last few days and a trend indicator (rising, falling, stable).

In search results, CardScope color codes cards by price trend. Green means falling price (good buying opportunity), red means rising price.

All data is stored locally in IndexedDB. This builds up a personal price history over time that helps you identify long term trends.

CardScope is useful for different user groups.

Collectors use the price history to find the best time to buy. If the price of a desired card has been falling for weeks, that is a good signal to act.

Sellers with large inventories use the portfolio overview to track the total value of their inventory. When certain cards increase in value, they can sell strategically.

Casual players use CardScope to quickly check the price range of a card before buying without having to manually compare multiple offers.

CardScope is built with JavaScript and stores all data locally in IndexedDB. There is no backend server and no external database. Price data is read from the publicly visible information on Cardmarket.

CardScope works entirely locally in your browser. No data is transmitted to external servers. Your Cardmarket login credentials are not read or stored.