Cart Optimizer for Cardmarket
The cheapest Cardmarket cart for your wants list
Cart Optimizer is a free Chrome extension for Magic: The Gathering and Yu-Gi-Oh! buyers. It finds the cheapest combination of sellers for your wants list, postage included, looking at sellers outside your cart too. It shows you the plan first, applies it to your Cardmarket cart in one click, then checks the final cart against the prediction.
Add to Chrome, it's freeMagic and Yu-Gi-Oh! · euro and pound accounts · ships to any Cardmarket country
A Shopping Wizard alternative that counts postage
Cardmarket's Shopping Wizard doesn't always build the cheapest cart. It can pick a pricier copy than your wants list needs, and spread your cards across more sellers than it has to, each one charging shipping. Cart Optimizer weighs every card's price against every seller's postage, and works out the cheapest combination of the offers it reads, keeping your wants list's language, condition, set, edition and foil settings.
How it works
- Open your Cardmarket cart, logged in as usual, and click the extension's icon. Pick your wants list.
- Press "Find savings". It reads the pages it needs in your own browser, usually in a few minutes. Or start from an empty cart and it finds the cheapest cart for the whole list.
- Check the plan and the cards you'll get, then press Apply. Your cart changes, and is checked against the prediction, seller by seller.
See it run
Playing it loads the video from YouTube. Or watch it on YouTube.
Real carts
Each row is a real Cardmarket cart from October 2026, with the total read from the cart after Apply. Time is how long the run took.
| Wants list | Ships to | Starting cart | Optimized | Saved | Time |
|---|---|---|---|---|---|
| Magic, EDHREC average Y'shtola deck (88 cards, no basic lands), from a Shopping Wizard cart | UK | £533.2724 sellers | £487.5320 sellers | £45.74 (9%) | ~18 min |
| Magic, 81 wants, a pre-release tester's own run | UK | £292.5325 sellers | £263.55 | £28.98 (10%) | — |
| Magic, 30 Commander staples, from a Shopping Wizard cart | Germany | €54.917 sellers | €44.579 sellers | €10.34 (19%) | ~10 min |
| Magic, 35 cards (German-language) shared on Reddit, from a Shopping Wizard cart | Germany | €134.0812 sellers | €124.2414 sellers | €9.84 (7%) | ~4.5 min |
| Yu-Gi-Oh!, 25 cards (Italian) shared on Reddit, from a Shopping Wizard cart | Italy | €178.6117 sellers | €171.4115 sellers | €7.20 (4%) | ~1.5 min |
| Yu-Gi-Oh!, the same 25 cards, from an empty cart | Italy | —empty | €171.4115 sellers | €24.23vs each card at its cheapest listing | ~1.5 min |
| Yu-Gi-Oh!, a Blue-Eyes deck (the developer's own list), from a Shopping Wizard cart | UK | £33.016 sellers | £11.115 sellers | £21.90 (66%) | ~2 min |
Savings depend on the list and where it ships. Lists of heavily reprinted cards, and carts spread over many sellers, save the most.
Questions
Is it safe?
It works in your own logged-in browser. It never asks for or sees your password, and never touches payment. The only thing it changes is your cart, and only when you press Apply. Its code isn't minified or obfuscated, so anyone can read exactly what it does. Always check your cart on Cardmarket before you pay: what you buy is your decision.
What does it read and send?
It reads only cardmarket.com: your cart, your wants list, and the card and seller pages it needs. Your name, address, account name and balance are removed from every page before anything is sent. The pages go to the extension's own server, which works out the cheapest cart. No ads, no analytics, nothing sold. The privacy policy says what's kept and for how long.
Why does it need access to cardmarket.com?
To read the same pages you'd open yourself, in your own session, and to change your cart when you press Apply. Chrome describes that as being able to "read and change" your data on Cardmarket.
Which games and currencies does it support?
Magic: The Gathering and Yu-Gi-Oh!, on euro and pound accounts, shipping to any Cardmarket country.
How big a list can it handle?
A run reads a limited number of pages. With "Also look at sellers outside your cart" on, lists of up to around 100 to 120 wants; with it off, around 200 or more. A bigger list still gets a plan, from the pages read before the limit, but it may miss some savings.
Is it free?
Yes, it's free to use.
How do I report a problem?
Press "Send feedback" in the extension's panel: leave "Include this run's details" ticked and we can see what went wrong. Or email [email protected].