I am creating an eshop and I am taking the approach of allowing the user to buy without having an account. However, there is a workflow which I am not sure what is the best practice.

A user can have only one shopping cart. Let's say that the user has some items in his cart and he signs out from my eshop. Then he comes back one day, adds some items to a cart as an anonymous user and then he remembers he has an account. Then he signs in. What should I do with the two carts?

  1. Keep the latest cart and delete the old one?
  2. Merge both carts into one and inform the user?
  3. Explain the situation to the user and have him decide what he wants to do (which one to keep or if he wants to merge them)?

I can think a situation where the user would want to merge them and another situation where he may want to keep just the last one. If I let him to decide he may be distracted from the whole process.

Does this depend on the eshop and the products? I haven't launch it yet, it will be a flower shop where I think most users will just buy one product, but that's just a guess. How do you handle situations like this? I checked multiple big eshops and most of them just merging the two carts.

  • If the first cart is "stale" (older than ... days) than just ignore it. If the first cart is recent enough: merge and tell the user you did so, giving them an easy option (single link) to undo what you just did for them. Feb 23, 2014 at 17:43

1 Answer 1


My recommendation is to Ask the user before you merge the two carts.

The reason is that there is a remote possibility that the two people might be sharing the same computer and one user might have created the preliminary cart and the second user might want to create his own cart and hence might log in. In this case if he finds that that there are additional items in his cart which he not planned for or accidentally purchases them, you are looking at a very bad user experience.

The advantage of asking the user before the merge is that you give him total control over the process and no point confuse him about how additional items appeared in the cart.

It also would follow Neilson's heuristics about the user being aware of the system status and also user freedom and control

  • If the user chose to merge the carts, clear out the guest cart and move the items to the account-linked cart. If the user chose to keep the carts separate, let the user continue shopping with the account-linked cart. Once the user signs out (or he is automatically signed out), revert to the guest cart. PS: Make sure you don't repeatedly ask the user about merging. Ask once, and ignore guest cart from then on.
    – ADTC
    Oct 14, 2016 at 8:01

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